Hydrothermal Synthesis Research Articles

2D Titanium Carbide (MXene): Band Gap Modulation

In the past few years, due to the growing demand for energy worldwide, research interest has been triggered to boost the photovoltaic performance of solar cells. Solar cells, the green energy processing media source, require an excellent absorber material to collect the incident photons and generate electrical energy. In this aspect, perovskite materials have been widely used as the absorber layer forming perovskite solar cells (PSC). Due to its tunable band gap, high charge transportation, reduced grain boundary and surface recombination properties, perovskite materials are extensively used in solar cells. Various research has been conducted on the upgradation of PSCs, mainly focusing on enhancing power conversion efficiency (PCE), stability, toxicity of Pb-based PSCs, less production cost, easy fabrication, and improved operation rate by reducing recombination of charge carriers. Several studies have been done to come up with appropriate electron/hole transport layers (ETL/HTL) arranged in a PSC. An advanced 2D hierarchical structure, MXene refer to transition metals carbides (C)/nitrides (N) or carbonitrides (CN). It has a general formula of Mn+1XnTx, where n = 1–3, M denotes the transition metals (Ti, Mo, Zr, Hf, Nb), X indicates C or N, and Tx indicates functional groups (–O, –OH, –F, –Cl). Owing to their unique optoelectronics properties, MXenes has proved itself to be a promising candidate for photovoltaic technology applications. MXenes are transparent, electrically conducting, have good charge mobility, and have an optimizable work function. The rich surface termination groups present on the MXene surface are uniform and offer great possibilities for tuning electrical properties. Also, the synthesis process of MXene makes it naturally functionalized, which alters the electrostatic potential, leading to a work function shift in thin films. For the first time, MXene was used in a perovskite solar cell in 2018, and since then, it has been explored in different ways. But MXene, being metallic in nature, offers nearly zero bandgap. So, various hybrid preparations or changes in the synthesis route should be opted to tune the bandgap of MXene. Thus, MXene-based composite, which offers a wide range of bandgap tunability, is extensively used as the light absorber material in various solar cells. In many research works, it is evident that intentionally introducing the required bandgap in metallic MXene makes it more useful for photovoltaic applications. Bandgap engineering is a very significant method to come up with different selective semiconductors for fabricating advanced photovoltaic devices. Solar intensity mainly falls in the range of infrared and visible part of the spectrum. Accordingly, the ideal bandgap of the active material should be roughly 1.2-1.6 eV. Therefore, the recent research aims to prepare 2D MXene semiconductors that have good absorption in this range with suitable bandgap. In this work, we synthesized a composite of MXene/multiferroic, taking bismuth ferrite (Ti3C2Tx@BiFeO3) nanocomposites via facile hydrothermal synthesis. To prepare the nanocomposites, we used two reducing agents: hydrazine hydrate (N2H4.H2O) and Ammonia (NH3.H2O). Through the same synthesis method but with different reducing agents, the resultant nanocomposite was noted to be different with two different multiferroics. When the MXene was prepared using N2H4.H2O, it resulted in (Ti3C2Tx@BiFeO3) and with NH3.H2O outcome was (Ti3C2Tx@Bi25FeO39) as shown in Figure 1. X-ray diffraction peak analysis showed proper composite formation. The characteristic peaks of layered MXene and bismuth ferrite were evident indicating no impurity formation and suitability of the synthesis route. Thorough bandgap studies of both MXene@multiferroic nanocomposite were done using reflectance spectra (Figure 2). In the range of 3000-8000 Å, reflectance spectra were seen to be continuous for (Ti3C2Tx@BiFeO3), but a reflectance edge was observed for (Ti3C2Tx@Bi25FeO39), indicating it as a better light absorber. Using Tauc’s plot and the kubelka-Munk equation, i.e., Eg = hν − [F (R (∞)) hν]2, the direct bandgap of (Ti3C2Tx@Bi25FeO39) was obtained as 2.2 eV. The analyzed reports point towards a new possibility of researching more on preparing 2D semiconducting MXene composite with a wide bandgap using a suitable reducing agent and weight percentage, which is crucial for solar cell application. Creating a modified MXene composite, which is non-toxic, cheap, provides favourable bandgap and can be commercially produced, is highly challenging. This work addresses such challenges and gives a different direction to the current work on the band gap modulation of 2D titanium carbide (MXene). REFERENCES: [1] Koneru, Bhargavi, Jhilmil Swapnalin, Srinivasan Natarajan, Adolfo Franco Jr, and Prasun Banerjee. "Intercalation of nanoscale multiferroic spacers between the two-dimensional interlayers of MXene." ACS omega 7, no. 23 (2022): 20369-20375. Figure 1

Iso-elemental SnO/SnO2 heterojunction composites for enhanced formaldehyde gas sensing

Heterojunction composite structures engineered with homo-metallic elements are an effective strategy for boosting gas sensing capabilities due to their ability to effectively reduce the contact barrier for charge transfer. In this study, iso-elemental SnO/SnO2 micro-rod composites were fabricated through hydrothermal synthesis followed by calcination. The gas sensing performance revealed that SnO/SnO2 microstructure when calcined at 400 °C (referred to as M1-400), displays remarkable long-term stability, with a response value of 21.05 and the quickest recovery time of 38 s–100 ppm of formaldehyde (HCHO) at 320 °C, outperforming other sensors. Further investigation indicates that the enhanced sensitivity of M1-400 can be attributed to the p-n heterojunction of SnO–SnO2 facilitating electron transport, and its increased adsorption affinity for HCHO due to higher vacuum and oxygen content. This synthesis strategy for SnO/SnO2 suggests that this material is promising for HCHO gas sensing applications and could offer a potentially straightforward method for preparing one-dimensional metal oxides.

One-Pot Synthesis of (CrMnFeCoNi)Ox High-Entropy Oxides for Efficient Catalytic Oxidation of Propane: A Promising Substitute for Noble Metal Catalysts.

The efficient catalytic oxidation of propane, as a short-chain alkane, remains challenging in environmental catalysis. High-entropy oxides (HEOs) exhibit advantages in abundant and well-dispersed elemental composition, exceptional thermal stability, and enriched lattice defects. Herein, (CrMnFeCoNi)Ox HEO catalysts are successfully synthesized by using a continuous hydrothermal flow synthesis (CHFS) route, without any subsequent calcination processes. This route yields HEOs with fine particle sizes, high specific surface areas, and abundant near-surface lattice oxygen compared to the traditional coprecipitation method. Notably, the propane conversion over the CHFS-made (CrMnFeCoNi)Ox HEO reaches 90% at 255 °C, with an apparent activation energy of 53.2 kJ/mol, mainly attributed to its enriched lattice oxygen and enhanced oxygen mobility that prevent the accumulation of acetates and the consequent occupation of active sites. In comparison to commercial Pt/Al2O3 and Pd/Al2O3, (CrMnFeCoNi)Ox HEO demonstrates exceptional activity and can maintain long-term stability under high-temperature (upon 650 °C) and moisture-rich conditions (at 2-10 vol %). These attributes highlight its potential as a promising substitute for noble metal catalysts in industrial applications.

Green hydrothermal synthesis of gallic acid carbon dots: characterization and cytotoxic effects on colorectal cancer cell line

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths worldwide, necessitating the development of novel therapeutic approaches. Carbon dots (CDs) have emerged as promising nanoparticles for biomedical applications due to their unique properties. Gallic acid (GA), an anticancer agent, is effective against various tumor types. This study explores the potential of gallic acid-derived carbon dots (GA-CDs) as an innovative anticancer agent against HCT-116 CRC cells, focusing on apoptosis signaling pathways. GA-CDs were synthesized using a one-pot hydrothermal method. Characterization was conducted using transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet-visible (UV-vis) absorption spectroscopy. The cytotoxicity of GA and GA-CDs on HCT-116 cells was evaluated using the MTT assay at various concentrations over 24 and 48 h. Cellular uptake was assessed via fluorescence microscopy, and apoptosis was analyzed using acridine orange/propidium iodide (AO/PI) staining. Total RNA extraction followed by complementary DNA (cDNA) synthesis via reverse transcription-PCR was performed, and real time-PCR (Q-PCR) was conducted to examine the expression of apoptosis-related genes includingCaspase-3,Bax, andBcl-2. Characterization confirmed the successful synthesis of spherical GA-CDs. GA-CDs exhibited dose- and time-dependent cytotoxicity, with IC50 values of 88.55 μg ml-1for GA-CDs and 192.2 μg ml-1for GA after 24 h. Fluorescence microscopy confirmed the efficient uptake of GA-CDs by HCT-116 cells. AO/PI staining showed a significant increase in apoptotic cell numbers after treatment with GA-CDs. Q-PCR analysis revealed overexpression ofCaspase-3 andBaxgenes in GA-CD-treated cells, though no significant changes were observed in the expression ofBcl-2 or theBax/Bcl-2 ratio. GA-CDs demonstrated potent anticancer properties by inducing apoptosis and reducing cell viability in HCT-116 cells. These findings suggest the potential of GA-CDs as a novel therapeutic agent for CRC treatment, warranting further investigation into their mechanism of action andin vivoefficacy.

Investigation of the reaction time and hydrothermal synthesis route on the SSZ-13 zeolite particle crystallization and CO2 adsorption

This study investigates the influence of synthesis time (1–4 days) and synthesis route for the fast production of SSZ-13 zeolites via the conventional hydrothermal method for CO2 adsorption. Two synthesis routes were examined using different Si precursors: tetraethyorthosilicate (Route T) and silica (Route L). The samples were characterized by XRD, FTIR, SEM, 29Si and 27Al MAS-NMR, and gas sorption, the results were correlated to CO2 adsorption kinetics. Route T produced fully crystalline SSZ-13 zeolite within 1 day with high yield, resulting in ultramicroporous materials through particle-mediate crystallization, transitioning from coarse spherical particles with high specific surface area (750 m2 g−1) and the highest equilibrium CO2 adsorption capacity of 81.08 mg g−1, to perfectly cubic structures for longer synthesis with decreased specific surface area (610 m2 g−1) and porosity. A disorder-to-order transition for synthesis longer than 3 days, along with the elimination of the interspaces internal, significantly decreased CO2 adsorption capacity (63.03 mg g−1). Meanwhile, SSZ-13 zeolites by Route L produced ultramicroporous crystalline particles only after 2 days, featuring intricate, layered structures formed by stacked sheets, indicating layer-by-layer mechanism. Longer synthesis times further increased particle complexity, reaching specific surface area of 858 m2 g−1 for the 4-day synthesis, along with improved CO2 adsorption capacity. However, the CO2 adsorption capacity for highly crystalline SSZ-13 samples obtained by Route L varied within 68.72–80.39 mg g−1, suggesting that structural properties also influenced CO2 adsorption performance. These findings demonstrate that conventional hydrothermal synthesis can rapidly produce SSZ-13 adsorbents, allowing fine-tuning material properties and CO2 adsorption capacity by selecting the appropriate synthesis route.

Exploring the harmful textile and pharmaceutical industries pollutant degradation mechanism and biological applications of MgO – SiO2 nanocomposite for environmental sustainability

<p style="line-height:150%;text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;">This article represents the photocatalytic activity of harmful pollutants from textile and pharmaceutical industries and compares the photocatalytic efficiency between pure MgO and MgO – SiO<sub>2</sub> nanocomposite. The MgO NPs are synthesized using hydrothermal synthesis, in which the extract from </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;">Nerium oleander</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;"> flowers is utilized as a reducing agent. The SiO<sub>2</sub> NPs were synthesized from the natural source of bamboo leaves by sol-gel method. Then, the composite is made by simply stirring and sonicating MgO and SiO<sub>2</sub> NPs. Then the prepared nanocomposite and pure MgO were analyzed for the crystalline nature (XRD), morphology (FE-SEM), particle size (DLS), Functional groups (FTIR), elemental composition (EDAX), optical properties (UV-vis spectroscopy). The above studies provide excellent MgO NPs and MgO – SiO<sub>2</sub> composite characteristics. The prepared MgO and MgO - SiO<sub>2</sub> were utilized for the photocatalytic activity of textile and pharmaceutical pollutants up to 90 and 120 mins, respectively, under sunlight irradiation. After degradation, the photocatalysts were tested to find their stability and reusability for five cycles. As discussed above, the MgO – SiO<sub>2</sub> performs better than pure MgO regarding pollutant degradation and stability. The prepared MgO and MgO – SiO<sub>2</sub> have been examined for antibacterial activity, exposing better results than the standard antibacterial agent (</span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;">Streptomycin</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;">). </span></p>

Surface facet engineering of ZnIn2S4 via supercritical hydrothermal synthesis for enhanced NO gas sensing performance

In this study, we investigate the novel application of ZnIn2S4 as an NO gas detection device by precisely modulating its surface facets through crystal growth control in a supercritical water environment. The supercritical hydrothermal synthesis successfully transforms ZnIn2S4 from a flower-like structure into a hexagonal plate morphology, driven by the preferential growth of the basal plane (003) surface facet. This morphological control, which is unattainable in a subcritical environment, is evidenced by a substantial increase in the (003)/(011) facet ratio from 0.52 to 1.98 with rising temperature. NO detection results indicate that this surface morphology modification significantly accelerates sensor response, attributed to enhanced interaction between the ZnIn2S4 surface and NO gas, as well as reduced diffusion limitations compared to the flower-like morphology. The hexagonal plates exhibit a remarkably fast response time of approximately 25 s, in contrast to 181 s for the flower-like counterpart. These findings underscore the crucial role of surface facet engineering in optimizing the gas-sensing properties of ZnIn2S4, highlighting its potential for advanced gas sensor applications.

NiFe2O4@SiO2 superparamagnetic nanoparticles as contrast agents in image-guided adaptive brachytherapy (IGABT)

Focusing on the study of superparamagnetic iron oxide samples for applications as contrast agents, the potential utility of NiFe2O4@SiO2 sample as a contrast agent in image guided adapted brachytherapy (IGABT) treatments is described here. This magnetic sample was prepared by controlled hydrothermal synthesis with urea addition and further TEOS reaction using the Stöber method. X-ray patterns show diffraction maxima indexed to a cubic symmetry of S. G. Fd-3m with Z = 8, compatible with an inverse spinel-type structure. Polyhedral shape particles with a size of about 21 ± 5 nm, together with a homogeneous silica coating of 12.7 ± 1 nm thickness were observed in TEM images Catheters and plastic needles containing NiFe2O4@SiO2 sample in agarose solution mixture were investigated. Images obtained by magnetic resonance imaging (MRI), computed tomography (CT) and X-ray of the ovoid applicator containing NiFe2O4@SiO2 sample in agarose solution mixture, suggest that this sample may be useful for visualizing the source path by performing a T2 weighted MRI and without the need to acquire a CT image. This process reduces uncertainties due to patient movements between imaging modalities as well as procedure time. MRI and CT images of the interstitial needles filled with this solution at different concentrations confirm that it is also suitable for use as a contrast agent. Finally, the investigated sample-agarose mixture was also inserted into a block of human-like pork tissue to approximate an “in vivo” experimentation. The results suggest that the studied sample may be useful in IGABT treatments and intraoperative BT where a series of catheters are implanted into the surgical cavity. Currently, the contrast agents used are not visible inside plastic needles. Our study shows that no toxicity is introduced into the system since the sample is contained within plastic catheters and never encounters the tissue.

Gallium hydroxide coated Ti3C2Tx MXene for high-performance asymmetric supercapacitor

Ti3C2Tx MXenes have emerged as promising candidates for energy storage applications due to their two-dimensional structure, metallic conductivity, tunable surface functionalities, and intrinsic pseudocapacitive charge storage. This study explores the hydrothermal synthesis of GaOOH/Ti3C2Tx composites using gallium nitrate as the gallium precursor. The incorporation of GaOOH not only expands the interlayer spacing of Ti3C2Tx, facilitating more efficient electrolyte ion migration, but also enhances the material's energy storage capacity by introducing additional active sites and augmenting pseudocapacitance. As an electrode material in supercapacitors, GaOOH/Ti3C2Tx composites, prepared with a 0.06 M gallium source concentration, achieve a remarkable specific capacitance of 542.1 F·g−1, surpassing that of pristine Ti3C2Tx (305 F·g−1), with a minimal degradation of only 3.4 % after 5000 charge-discharge cycles. This research offers valuable insights into the electrochemical behavior of GaOOH/Ti3C2Tx composites and highlights the role of GaOOH in enhancing the performance of these materials. The results underscore the potential of combining metal hydroxides with MXenes for advanced supercapacitor applications.

Enhanced Cyanide Oxidation to Cyanate via Photocatalytic Ozonation: Comparing Sol–Gel and Hydrothermal Synthesis of BiVO4 Catalysts

Bismuth vanadate has been reported as a promising active semiconductor for visible light harvesting. However, the rapid recombination of charge carriers has limited its photocatalytic properties. As an alternative route to treat contaminated water containing cyanide ions, photoactivated BiVO4 in combination with ozone has been investigated. BiVO4 photocatalysts were synthesized by microwave-assisted hydrothermal method, as well as by sol–gel, obtaining the monoclinic crystalline structure and a band gap of ~ 2.5 eV by XRD and UV–Vis DRS. The morphological analysis, elemental chemical composition, BET surface area, stability, and photoluminescence characteristics were carried out for both samples. Although the majority composition belongs to BiVO4, the presence of secondary phases was confirmed by XPS. The BiVO4 obtained by sol–gel (sol–gel BVO) exhibited superior photocatalytic performance with a lower reaction time (15 min) to oxidize free cyanide under visible-light radiation in combination with ozone. The degradation kinetics is described by pseudo-zero-order kinetics, and the rate constant (k0) of BiVO4 synthesized by microwave-assisted hydrothermal method was found to be the lower of the two. The high efficiency of the photocatalytic ozonation for the removal of free cyanide can be ascribed to a combination of two oxidation systems and the synergy of both processes.

Ultrathin Ni(OH)2 nanosheets: Microemulsion assisted hydrothermal synthesis and application in advanced hybrid supercapacitors

Nickel hydroxide (NH) has garnered considerable attention in supercapacitors due to its large theoretical capacity, low cost, and eco-friendliness. However, insufficient accessible surface area and poor cyclic stability have hindered its large-scale application. In this study, ultrathin NH nanosheets were synthesized using a microemulsion-assisted hydrothermal strategy. The H2O/EtOH volume ratio (K(H2O/EtOH)) significantly influences the specific surface area (SA) of the prepared NH nanosheets. The Ni(OH)2 nanosheets (NH-1–1) exhibited a thickness of ca. 4 nm and a remarkable SA of 285.0 m2 g–1 at a K(H2O/EtOH) value of 1/1. The NH-1–1 electrode demonstrated an impressive specific capacity of 824.5 C g–1 at a current density of 500 mA g–1. Additionally, the NH-1–1//activated carbon hybrid supercapacitor (NH-1–1//AC HSC) delivered 91.3 F g–1 at 500 mA g–1 with an energy density of 34.5 Wh kg–1 at 412.5 W kg–1. Even when the power density was increased to 8,250 W kg–1, the NH-1–1//AC HSC still provided 22.4 Wh kg–1. After 20,000 consecutive cycles at 5.0 A g–1, the capacitance retention of this device was 89.5 %. Impressively, the NH-1–1//AC HSC operated a clock for ca. 32 min. The exceptional energy storage capability of the NH-1–1 is attributed to its large SA and ultrathin structure.

Multichannel antibacterial 3D@2D membrane for water treatment

New membrane materials with excellent water permeability and high dyes rejection are crucial. Metal-organic frameworks (MOFs) stand out as promising candidates due to their diverse chemistry and topology. In this study, three-dimensional MOFs were grown on two-dimensional lamellar porous graphene (PG) using an in situ hydrothermal synthesis method to create hybrid nanomaterials. These nanomaterials were then incorporated into the active layers of the composite nanofiltration membranes through a filter-press assisted assembly. The resulting membranes demonstrated high dye rejection (>99.8 %) and permeability to inorganic salts (e.g., 51 % for Na2SO4 and >90 % for NaCl, MgCl2 and MgSO4) attributed to size-sieving and electrostatic-repulsion mechanisms, along with high permeability (19.8 LMH bar−1). This membrane also demonstrated a good stability in continuing operation for 54 h. Moreover, the membrane material exhibited excellent antibacterial properties. These advantages highlight the effectiveness of the 3D material and 2D material structure with specific channels, rendering the membranes highly versatile.

Semi-carbonized fluorinated polyimide-assisted preparation of TiO2 with strikingly boosted photocatalytic CO2 reduction performance

In this study, oxygen vacancies (OVs)-enriched TiO2 photocatalysts were facilely obtained using a hydrothermal synthesis with the assistance of semi-carbonized fluorinated polyimide (FPI). Addition of FPI has influenced the crystal growth of TiO2, promoting the formation of abundant OVs in TiO2. OVs enhance separation of photogenerated charges and light absorption of TiO2. Moreover, photocatalytic CO2 reduction experiments demonstrate that CO conversion on the 6 % sample (mass ratio of FPI to TiO2 is 6 %) is 2.9 times higher than that on the reference TiO2 under a xenon lamp illumination for 4 h Even after 4 cycles of photocatalytic CO2 reduction, the 6 % sample still has a high CO conversion rate. This work provides a viable pathway for the development of highly performance TiO2-based photocatalysts to promote the conversion of CO2 into high-valent carbon-containing compounds.

Unveiling Morphology-Structure Interplay on Hydrothermal WO3 Nanoplatelets for Photoelectrochemical Solar Water Splitting.

Photoelectrochemical (PEC) water splitting offers a sustainable route for hydrogen production, leveraging noncritical semiconductor materials. This study introduces a seed layer-free hydrothermal synthesis approach for semiconductor photoanodes based on tungsten trioxide (WO3) nanoplatelets. Aiming to boost the efficiency of photoelectrochemical water splitting through optimization of the synthesis parameters of bare WO3, focusing on temperature, time, and layer thickness, we systematically explored their effects on the morphological, structural, and optical characteristics of WO3 photoanodes. Combining a low-temperature regime (90 °C for 12 h) with a multilayer strategy (up to six-layers) resulted in significant improvements in photocurrent. Particularly, the five-layer sample exhibited a remarkable increase of over 70% compared to the single-layer photoanode. Morphological aspects, particularly the fractal dimension of nanoplatelets and the emergence of the (220) crystalline orientation, usually neglected, were found to play pivotal roles in modulating the PEC response. Rietveld refinement of X-ray diffraction patterns further underscored the importance of crystallographic facets, volume unit cell expansion, and microstrain in influencing photocurrent outcomes. Furthermore, we adapted the Mott-Schottky equation to incorporate the fractal dimension reflecting the nanostructures' nature, usually set to a planar interface. Our findings highlight the interchange between nanoplatelet morphology and structural parameters in determining the PEC efficiency of WO3 photoanodes.

Prebiotic Nucleoside Phosphorylation in a Simulated Deep-Sea Supercritical Carbon Dioxide-Water Two-Phase Environment.

Prebiotic synthesis of complex organic molecules in water-rich environments has been a long-standing challenge. In the modern deep sea, emission of liquid CO2 has been observed in multiple locations, which indicates the existence of benthic CO2 pools. Recently, a liquid/supercritical CO2 (ScCO2) hypothesis has been proposed that a two-phase ScCO2-water environment could lead to efficient dehydration and condensation of organics. To confirm this hypothesis, we conducted a nucleoside phosphorylation reaction in a hydrothermal reactor creating ScCO2-water two-phase environment. After 120 h of uridine, cytosine, guanosine, and adenosine phosphorylation at 68.9°C, various nucleoside monophosphates (NMPs), nucleotide diphosphates, and carbamoyl nucleosides were produced. The addition of urea enhanced the overall production of phosphorylated species with 5'-NMPs, the major products that reached over 10% yield. As predicted, phosphorylation did not proceed in the fully aqueous environment without ScCO2. Further, a glass window reactor was introduced for direct observation of the two-phase environment, where the escape of water into the ScCO2 phase was observed. These results are similar to those of a wet-dry cycle experiment simulating the terrestrial hot spring environment, indicating that the presence of ScCO2 can create a comparatively dry condition in the deep sea. In addition, the high acidity present in the aqueous phase further supports nucleotide synthesis by enabling the release of orthophosphate from the hydroxyapatite mineral solving the phosphate problem. Thus, the present study highlights the potential of the unique ScCO2-water two-phase environment to drive prebiotic nucleotide synthesis and likely induce condensation reactions of various organic and inorganic compounds in the deep-sea CO2 pool on Earth and potentially other ocean worlds.

Dodecylamine‐Assisted Hydrothermal Synthesis of Carbon‐Supported Ultrafine IrRu Nanoparticles for Oxygen Evolution Electrocatalysis and Overall Water Splitting

AbstractRuthenium (Ru)‐ and iridium (Ir)‐based nanomaterials have always been regarded as efficient electrocatalysts for oxygen evolution reaction (OER) in acidic electrolytes. Herein, we develop a facile dodecylamine‐assisted hydrothermal synthesis for producing carbon‐supported IrRu alloy nanoparticles with controllable Ir/Ru ratios and ultrafine sizes towards high‐efficiency OER and overall water electrolysis. In this strategy, the dodecylamine that serves as a capping and reducing agent enables the final IrRu alloy nanoparticles to possess average sizes <3 nm and high degree of dispersion on carbon substrate. By combining high OER activity of Ru with high acidic robustness of Ir, the as‐prepared IrRu/C nanoparticles at a suitable Ir/Ru ratio of 1/3 show good activity and durability for the OER electrocatalysis and overall water splitting. In specific, the Ir1Ru3/C catalyst exhibits the lowest overpotential of 302 mV at the current density of 10 mA cm−2 and the highest mass activity of 120.5 mA mg−1 at 1.532 V for OER in 0.5 M H2SO4 electrolyte. In addition, a two‐electrode acidic electrolyzer assembled with Ir1Ru3/C at anode and commercial Pt/C at cathode (Pt/C|| Ir1Ru3/C) exhibits a low cell voltage of 1.44 V for achieving the current density of 10 mA cm−2, along with a satisfied 20h durability.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

AbstractPhotocatalytic CO2 reduction serves as an important technology for value‐added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two‐dimensional/two‐dimensional (2D/2D) p‐n heterojunction CuS‐Bi2WO6 (CS‐BWO) with highly connected and matched interfacial lattices was designed in this work via a two‐step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p‐n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high‐coverage key intermediate b‐CO32−, while CuS (CS) acted as a broad light‐harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p‐n heterojunction CS‐BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g−1 h−1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS‐BWO samples. This work provided an innovative design strategy for developing high‐activity heterojunction photocatalyst for converting CO2 into value‐added solar fuels.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels.

Photocatalytic CO2 reduction serves as an important technology for value-added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi2WO6 (CS-BWO) with highly connected and matched interfacial lattices was designed in this work via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high-coverage key intermediate b-CO3 2-, while CuS (CS) acted as a broad light-harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g-1 h-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO samples. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO2 into value-added solar fuels.

Optimizing Cu 3d Bands with Nanotubular SnO2 to Boost Their Catalytic Transfer Hydrogenation Activity.

Catalytic transfer hydrogenation (CTH) using Cu nanocatalysts offers significant advantages over direct high-pressure hydrogenation. However, the active hydrogen (H*) in this process exhibits poor adsorption and tends to release H2 readily due to the fully occupied 3d states of Cu. To address this issue, a tubular SnO2 support with electron-accepting ability was selected to host Cu nanoparticles, aiming to optimize the Cu 3d bands. The Cu/SnO2 nanohybrids were prepared through an electrospinning technique, followed by hydrothermal synthesis. As evidenced by X-ray photoelectron spectroscopy (XPS) binding energy shifts and density functional theory (DFT) simulations, some electrons from Cu transferred to SnO2 in the Cu/SnO2 nanohybrids due to their different work functions. Such electron transfer enables the Cu 3d orbitals to lose electrons and alters its valence configuration from 3d10 to 3d10-x, which enhances the adsorption of active H* atoms and thereby inhibits undesirable H2 release. The 15 wt % Cu/SnO2 exhibits improved catalytic hydrogenation of 4-nitrophenol with NaBH4, with an optimal normalized rate constant of 56.98 mg-1 min-1 and a turnover frequency of 4.82 min-1, surpassing most reported catalysts. The enhanced activity is attributed to the optimized electronic states, improved hydrogen adsorption, and the tubular structure of the support. This work might shed light on developing more non-noble metal nanocatalysts for CTH by tuning their d bands with appropriate oxide supports.

Enhanced Photo-Fenton Degradation of Antibiotics through Internal Electric Field Formation at the Interface of Mixed-Phase FeS₂

Article Enhanced Photo-Fenton Degradation of Antibiotics through Internal Electric Field Formation at the Interface of Mixed-Phase FeS₂ Hongyan Liu 1,2, Yunhang Shao 1,2, Shuai Dou 1,2 and Chengsi Pan 1,2,* 1 Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China 2 International Joint Research Center for Photoresponsive Molecules and Materials, Jiangnan University, Wuxi 214122, China * Correspondence: cspan@jiangnan.edu.cn Received: 9 September 2024; Revised: 9 October 2024; Accepted: 13 November 2024; Published: 15 November 2024 Abstract: Iron sulfide (FeS₂) is a rich mineral resource widely used as an efficient Fenton and photo-Fenton reagent due to its non-toxicity and low synthesis cost. However, the mechanism underlying its photo-Fenton degradation activity related to the two crystal phases—pyrite (P-FeS₂) and marcasite (M-FeS₂)—is still not well understood. In this study, P-FeS₂, M-FeS₂, and their mixed phase (P/M-FeS₂) were prepared through hydrothermal reactions. The results showed that P/M-FeS₂ exhibited the highest photo-Fenton degradation activity, achieving a removal rate of approximately 99% for 50 ppm of ciprofloxacin (CIP) within 3 minutes, outperforming other photo-Fenton catalysts in pollutant degradation. The study revealed that an internal electric field (IEF) is generated at the interface of M-FeS₂ and P-FeS₂ due to their differing work functions. This IEF accelerates the regeneration of the active sites (Fe²⁺ in S₂²⁻-P-FeS₂ and M-FeS₂) required for the Fenton reaction, thereby explaining the superior activity of the P/M-FeS₂ mixed phase. This study introduces the IEF theory for the first time to explain the mechanism of mixed-phase catalysts in the photo-Fenton reaction. The formation of IEF can enhance the regeneration of the active sites involved in the Fenton reaction, thereby improving both reaction activity and stability. This work highlights the significance of regulating crystal phases in the degradation of pollutants during heterogeneous Fenton reactions and offers insights for developing highly efficient Fenton catalysts.