High H2 Generation Research Articles

Mesoporous Fe2O3-TiO2 Integrated with Plasmonic Ag Nanoparticles for Enhanced Solar H2 Production.

Present work describes a sol-gel assisted one-pot synthesis of mesoporous Fe₂O₃-TiO₂ nanocomposites (TiFe) with different Ti:Fe ratios, and fabrication of Ag-integrated with TiFe nanocomposites (TiFeAg) by a chemical reduction method and demonstrated for high solar H2 generation activity in direct sunlight. Enhanced solar H2 production is attributed to the light absorption from entire UV+Visible region of solar spectrum combined with Schottky (Ag-semiconductor) and heterojunctions (TiO2-Fe2O3), as evidenced from HRTEM and various characterization studies. TiFeAg-2 thin film (1 wt% Ag-loaded TiFe-4) displayed the highest activity with a solar H2 yield of 7.64 mmol h⁻¹g⁻¹, which is 48 times higher than that of bare TiO₂ and 5 times higher in thin film form compared to its powder counterpart. Schottky and heterojunctions formed at the interface efficiently separate the charge carriers and increase the hydrogen production activity. The highest H2 production activity of TiFeAg-2 is partly attributed to the heterogeneous distribution of Fe3+ and metallic Ag-species with relatively high Ag/Ti surface atomic ratio. A plausible photocatalytic reaction mechanism on TiFeAg nanocomposite may involve the direct electron transfer from both Fe2O3 and TiO2 to Ag nanoparticles which are subsequently utilized for the reduction of H+ to H2.

Geminal Synergy in Pt-Co Dual-Atom Catalysts: From Synthesis to Photocatalytic Hydrogen Production.

Dual-atom catalysts (DACs) have garnered significant interest due to their high atom utilization and synergistic catalysis. However, developing a precise synthetic method for DACs and comprehending the underlying catalytic mechanisms remain challenging. In this study, we employ a photoinduced anchoring strategy to precisely synthesize PtCo DAC on graphitic carbon nitride (CN). A Co atom was anchored on CN through the lone-pair electrons of nitrogen. Upon light irradiation, photoelectrons gathering at the Co site can anchor Pt metal ions nearby, accurately facilitating the formation of heteronuclear DACs. The PtCo DAC demonstrates a remarkably high H2 generation rate from ammonia borane (AB) hydrolysis, with a TOF of 3130 molH2 molPt-1 min-1 at 298 K. This TOF value is approximately 3.2 times higher than that of the Pt single-atom photocatalyst. Importantly, the PtCo DAC shows good stability, achieving a turnover number as high as 307,982 molH2 molPt-1 at room temperature. The experimental and theoretical calculation results demonstrate that the synergy between Pt and Co optimizes the adsorption energy of AB and H2 molecules while reducing the energy barrier of the rate-determining step, thus accelerating H2 evolution from AB hydrolysis. Additionally, the introduced Co species stabilize the Pt active sites by enhancing the stability of the Pt-N bond, preventing leaching, aggregation, and deactivation. The excellent catalytic performance, good stability, and low cost of the catalysts in this work open new prospects for their practical application in hydrogen production.

Building Mo2C/C/TCN heterojunction for efficient noble-metal-free plastic photoreforming and hydrogen generation

Photocatalytic water splitting converts sunlight directly to storable H2, but commonly involves the use of a hole sacrificial agent and a noble metal cocatalyst, leading to the waste of energy and increasing cost. Herein, we report a Mo2C/C/TCN heterojunction for overcoming these shortages through a combination system to realize H2 generation and plastic reforming at the same time. Mo2C/C/TCN, consisting of thiophene-embedded polymeric carbon nitride (TCN) and molybdenum carbide anchored on graphite nanosheet (Mo2C/C), was prepared via electrostatic self-assembly. In the heterojunction, TCN performed as an electron donor, Mo2C acted as an electron acceptor and H2 evolution active center, while the graphite (C) in Mo2C/C served as an electron transport medium. Owing to its hetero-structure, the visible light utilization efficiency as well as photoinduced charge separation and migration efficiency of the catalyst Mo2C/C/TCN were greatly strengthened compared to the pristine polymeric carbon nitride (CN). As a result, Mo2C/C/TCN exhibited satisfactory visible-light-driven waste plastic photoreforming and high H2 generation activity. The optimized photocatalytic H2 evolution rate over Mo2C/C/TCN reached 188.7 μmol h−1, which was 7.1 times of that over Pt/CN in 10 vol% triethanolamine (TEOA), far ahead of the research that has been reported. Additionally, Mo2C/C/TCN exhibited adorable photoreforming efficiency of polylactic acid (PLA) and bisphenol A (BPA) under visible light. This work provides an efficient approach for lowering cost, enhancing optical absorption, and inhibiting charge recombination for higher photocatalytic performance and wilder applications.

Novel CoFe2O4 / LaAlO3 nanocomposites: An impressive photocatalyst with p-n hetero-junction for improved H2 generation under visible exposure

The present work is devoted to the synthesis of perovskite LaAlO3 by Sol-Gel approach and its application for the photo-evolution of H2 in conjunction with cobalt ferrite CoFe2O4 prepared by nitrate route. The thermal analysis (TG/DSC) showed that the formation is completed at 600 °C. The X-ray diffraction (XRD) pattern is characteristic of a single phase, crystallizing in a rhombohedral symmetry with a crystallite size of 36 nm. The SEM micrographs revealed a homogeneous structure with an agglomeration of shaped grains (40–80 nm). The forbidden band (3.39 eV), calculated from diffuse reflectance data, is assigned to the ligand charge transfer O2−: 2p → Al3+: 3s orbital. As prepared, LaAlO3 is an n-type semiconductor as demonstrated from the capacitance - potential (C−2 - E) graph with an electron density of 9.4 × 1014 cm−3 due to oxygen under-stoichiometry. Attention was directed to photo-electrochemistry in connection with water reduction into hydrogen. With a negative conduction band potential (−0.11 VSCE), H2 generation can be synergized over the hetero-system by visible light. The photocatalytic capability of CoFe2O4 25%/LaAlO3 revealed a high H2 generation of 963 μmol g−1 in the alkaline electrolyte (NaOH, 0.1 M) with a catalyst dose of 1 mg mL−1, which is 1.3 times more than CoFe2O4 under similar conditions. Photoactivity is significantly improved by 60%, up to 2400 μmol g−1 in the presence of oxalate C2O42− as a hole scavenger in the hetero-junction, two hydrogen release tests were successfully recorded. The higher H2 production in the hetero-junction system is attributed to the lower recombination rate of electron/hole (e−/h+) in the material, due to the large band bending at the solid interfacial.

MOF derived cobalt-phospho-boride for rapid hydrogen generation via NaBH4 hydrolysis

Developing effective transition metal catalysts that can replace precious metal-based catalysts for hydrogen generation from the hydrolysis of chemical hydride has attracted extensive interest. This study focuses on synthesizing cobalt phospho-boride (CoPB) within a metal-organic framework (MOF) framework using hydrothermal and chemical reduction methodologies. Incorporating boron and phosphorous into Co-MOF enhances the hydrogen generation rate, reaching 1.8 L/min/g and 3.6 L/min/g for CoB-MOF and CoPB-MOF, respectively, during NaBH4 hydrolysis. Along with the nanostructured morphology of MOF, the electron modulation around Co-sites due to the presence of P and B creates a synergic effect to produce this high H2 generation rate and very low activation energy of 20.7 kJ/mol. The kinetic studies on NaBH4 hydrolysis reaction revealed zero-order kinetics with respect to NaBH4 concentration for CoPB-MOF, where porous morphology renders facile movement of BH4− ions to the active sites. The heat treatment at 773 K in the N2 atmosphere did not show any significant fall in the activity of CoPB-MOF, thus showcasing its robust nature. Moreover, the present catalyst also displayed recycling behavior with no signs of deactivation.

Tuning dark fermentation operational conditions for improved biohydrogen yield during co-digestion of swine manure and food waste

Large amounts of swine manure (SM) and livestock waste production in South Korea, leading to enormous environmental pollution and requiring extensive treatment before discharge. To address these issues, the upstream dark fermentation (DF) technique provides a sustainable solution to recover biohydrogen (bio-H2) using solubilized organics; however, the process parameters need to be optimized to boost the yield. The modulation of process variables, including input chemical oxygen demand (COD) doses (2, 6.4, 10, and 12 g/L), pH (5, 5.5, and 6), hydraulic retention time (HRT: 4.5 days, 2 days, and 1 day), and cosubstrate (SM: food waste (FW) = 8:2), was studied to improve the performance of DF. Mixing FW and SM maintains the feedstock pH in the range of 5.8–6.21 in DF, boosting hydrogen (H2) production to 0.5 L, which is considerably higher than that in DF fed with individual substrates. Similarly, a higher H2 generation and hydrogen yield (HY) of 1.32 L/L/day and 275.57 mL/gVSadded, respectively, were obtained for HRT of 1 day compared to HRT of 2 days (H2 production of 0.830 L/L/day and HY of 159.05 mL/gVSadded) and 4.5 days (H2 production of 0.403 L/L/day and HY of 80.6 mL/gVSadded) in 5 L DF. The produced H2 had a high purity of 83.21%. Thus, DF with operational variables of HRT of 1 day and pH of 5.5–6.2 with cosubstrate feeding was found to be effective for boosting the bio-H2 yield and treatment efficiency. Such optimized process parameters guide the operation of scalable DF to keep the stability and equilibrium of the process and maximize the HY.

Microstructure driven charge carrier separation in superior thin g-C3N4 nanosheets towards enhanced photocatalytic activities

The performance of graphic carbon nitride (g-C3N4) depended strongly on solar energy harvesting and photogenerated charge carrier separation and transfer. Defect engineering (local component and crystallinity adjustment) helps g-C3N4 to improve photocatalytic activity. In this paper, superior thin g-C3N4 nanosheets with typical microstructures were created using a two-step thermal polymerization at high temperature by adjusting precursors. g-C3N4 nanosheets obtained using melamine revealed fine crystallinity compared with that created using dicyandiamide even though related flat microstructure observed for two samples. In contrast, a wrinkled microstructure with self-assembled amorphous/crystalline junctions was created by urea. Interestingly, the wrinkled one revealed the fastest degradation for RhB which was degraded over within 5 min and a high H2 generation rate of 3473 μmol·g−1·h−1 compared with other samples. This performance is ascribed that wrinkle ultra-thin g-C3N4 nanosheets with amorphous-crystalline junctions significantly improved light harvesting ability and photogenerated carrier separation and transport efficiencies. Furthermore, almost no H2 was generated using molten-salt (NaCl and KCl) assisted porous g-C3N4 nanosheets. These results suggest that increased active sites generated by defect engineering were crucial for the photocatalytic performance of g-C3N4. The detailed discussion on microstructure formation provides an important platform for the construction of highly efficient g-C3N4 based photocatalysts.

Construction of intramolecular and interfacial built-in electric field in a donor-acceptor conjugated polymers-based S-scheme heterojunction for high photocatalytic H2 generation

Engineering a robust built-in electric field (IEF) is favorable for boosting carrier separation and achieving high photocatalytic performance. Herein, we developed a donor-acceptor conjugated polymer-based S-scheme heterojunction, utilizing both intramolecular and interfacial IEF to enhance carrier separation and achieve superior photocatalytic performance. Specifically, the intramolecular IEF was established by introducing 1,6-dibromopyrene into carbon nitride (CN) to form 1,6-dibromopyrene grafted CN (CNPy). Concurrently, the S-scheme heterojunction was formed by coupling CNPy with CdSe nanoparticles to create an interfacial IEF. Experimental findings demonstrated that the combined effect of intramolecular and interfacial IEF within the CdSe/CNPy heterojunction significantly improved the carrier separation and retained strong redox capacity. Benefiting from these advantages, the optimized composite, 100%CdSe/CNPy-0.2, showed the highest H2 generation rate of 1.16 mmol·g−1·h−1, surpassing those of pure CNPy-0.2, CdSe and 100%CdSe/CN by 58, 2.2 and 2.32 times, respectively. This study introduces an innovative design strategy for IEF-regulated conjugated polymer-based materials, paving the way for efficient solar-to-chemical energy conversion.

Interfacial synergy between Pt3Co nanoparticles and CoO for efficient ammonia borane hydrolysis

Ammonia borane (AB, NH3BH3) with the high H2 content has been regarded as a promising material for chemical hydrogen storage. AB can hydrolyze to release H2 under the catalysis of noble-metal catalysts with high activity, but the high cost of noble-metals and their poor long-term stability prohibit the large-scale applications. Developing more cost-effective and stable catalysts by introducing cheap transition metal elements has been a promising strategy. Herein, we adopted a step-by-step precipitation method to synthesize bimetallic Pt-Co catalysts supported on rutile TiO2, which show significantly improved performance in AB hydrolysis reaction. The optimized 0.9Pt3.5Co/TiO2 catalyst (with the Pt and Co loadings of 0.9 and 3.5 wt%, respectively) exhibits an extremely high H2 generation rate, showing a turnover frequency value of 2163 molH2 molPt-1 min−1 at 298 K, 9 times higher than that of 0.9Pt/TiO2 catalyst and superior to those of most of the reported Pt-based catalysts. Structure characterizations and theoretical calculations reveal that the promoted AB hydrolysis performance arises from the interfacial synergistic effect between the supported Pt3Co alloy and cobalt oxide CoO, which accelerates the B-H bond cleavage and water activation, respectively. The excellent AB hydrolysis performance of the Pt-Co catalysts indicates the great prospects of alloy-oxide interfaces in the field of liquid phase chemical hydrogen storage.

Localized ultrafine Cu clusters within MOF-derived metal oxides for collective photochemical and photothermal H2 generation

The ability to prepare ultrafine metal cluster (UMC) in supported catalysts, which exhibit extraordinary physical and chemical properties offers exciting opportunities to tailoring catalytic performance. However, the fabrication of singly-dispersed metal cluster catalysts that are both catalytic stable and active remains challenging. In this work, ultrafine Cu clusters has been spatially immobilized within the MOF derived photocatalyst matrix to realize a unitary photocatalyst with high density and stable active sites for charge separation and photothermal co-functions. Furthermore, the embedded Cu is capable of overcoming challenges related to porous structure collapse, disparate material interfaces and incompatibility between light absorption and charge transfer processes. Resultantly, the photocatalyst (m-TiO2/Cu) exhibits a high and stable H2 generation rate of 17.8 mmolg−1h−1 that is ∼69 times higher compared to the control. In essence, this study presents an efficient approach to immobilize ultrafine metal active sites for the development of high-performance heterogeneous catalysts for energy applications.

Role of Efficient Charge Transfer at the Interface between Mixed-Phase Copper-Cuprous Oxide and Conducting Polymer Nanostructures for Photocatalytic Water Splitting.

Photocatalytic hydrogen generation from water splitting is regarded as a sustainable technology capable of producing green solar fuels. However, the low charge separation efficiencies and the requirement of lowering redox potentials are unresolved challenges. Herein, a multiphase copper-cuprous oxide/polypyrrole (PPy) heterostructure has been designed to identify the role of multiple oxidation states of metal oxides in water reduction and oxidation. The presence of a mixed phase in PPy heterostructures enabled an exceptionally high photocatalytic H2 generation rate of 41 mmol h-1 with an apparent quantum efficiency of 7.2% under visible light irradiation, which is a 7-fold augmentation in contrast to the pure polymer. Interestingly, the copper-cuprous oxide/PPy heterostructures exhibited higher charge carrier density, low resistivity, and 6 times higher photocurrent density compared to Cu2O/PPy. Formation of a p-p-n junction between polymer and mixed-phase metal oxide interfaces induce a built-in electric field which influences directional charge transfer that improves the catalytic activity. Notably, photoexcited charge separation and transfer have been significantly improved between copper-cuprous oxide nanocubes and PPy nanofibers, as revealed by femtosecond transient absorption spectroscopy. Additionally, the photocatalyst demonstrates excellent stability without loss of catalytic activity during cycling tests. The present study highlights a superior strategy to boost photocatalytic redox reactions using a mixed-phase metal oxide in the heterostructure to achieve enhanced light absorption, longer charge carrier lifetimes, and highly efficient photocatalytic H2 and O2 generation.

The Green Box: Selenoviologen-Based Tetracationic Cyclophane for Electrochromism, Host–Guest Interactions, and Visible-Light Photocatalysis

The novel selenoviologen-based tetracationic cyclophanes (green boxes 3 and 5) with rigid electron-deficient cavities are synthesized via SN2 reactions in two steps. The green boxes exhibit good redox properties, narrow energy gaps, and strong absorption in the visible range (370-470 nm), especially for the green box 5 containing two selenoviologen (SeV2+) units. Meanwhile, the femtosecond transient absorption (fs-TA) reveals that the green boxes have a stabilized dicationic biradical, high efficiency of intramolecular charge transfer (ICT), and long-lived charge separation state due to the formation of cyclophane structure. Based on the excellent photophysical and redox properties, the green boxes are applied to electrochromic devices (ECDs) and visible-light-driven hydrogen production with a high H2 generation rate (34 μmol/h), turnover number (203), and apparent quantum yield (5.33 × 10-2). In addition, the host-guest recognitions are demonstrated between the green boxes and electron-rich guests (e.g., G1:1-naphthol and G2:platinum(II)-tethered naphthalene) in MeCN through C-H···π and π···π interactions. As a one-component system, the host-guest complexes of green box⊃G2 are successfully applied to visible-light photocatalytic hydrogen production due to the intramolecular electron transfer (IET) between platinum(II) of G2 and SeV2+ of the green box, which provides a simplified system for solar energy conversion.

Chitosan hydrogel anchored phthalocyanine supported metal nanoparticles: Bifunctional catalysts for pollutants reduction and hydrogen production

Metal nanoparticles possess high catalytic activity in various organic transformation reactions. A catalyst must be recovered and re-used effectively and economically to lower the overall reaction cost. The recovery of a catalyst remains a challenge due to their extreme small size. In this research work, catalytic metal nanoparticles were synthesized on Zn-phthalocyanine (ZnPc) and chitosan hydrogel (CH) composite which acts as catalyst support. The ZnPc-CH support facilitate the easy recovery of the loaded metal nanoparticles. Metal nanoparticles (M0) based on Cu0, Ag0, Ni0, Co0 and Fe0 were decorated inside and on ZnPc-CH hydrogel surface. The developed M0@ZnPc-CH were utilized for the enhanced selective reduction of toxins and hydrogen production by methanolysis and hydrolysis of NaBH4. Effective catalytic reduction and hydrogen generation was successfully achieved with Co0@ZnPc-CH and ZnPc-CH. Under optimized conditions, Co0@ZnPc-CH showed complete reduction of 4-nitrophenol (4-NP) in 8.0 min with the fast 4-NP reduction kinetics (K = 0.611 min−1). Among the developed catalysts, ZnPc-CH showed fast H2 generation with high H2 generation rate (HGR = 4100 mLg−1min−1) under optimized conditions. Metal leaching from Co0@ZnPc-CH was negligible during recycling of the catalyst, suggesting that it could be implemented to 4-NP treatment from real water samples. Similarly, ZnPc-CH could produce same quantity of H2 throughout 4 continuous cycles of durability testing without any deactivation and leaching and ZnPc-CH showed high stability, indicating the effectiveness of the catalyst to be applied for H2 production on large scale.

Surface Engineering of TiO2 Nanosheets to Boost Photocatalytic Methanol Dehydrogenation for Hydrogen Evolution.

Low-cost high-efficiency H2 evolution is indispensable for its large-scale applications in the future. In the research, we expect to build high active photocatalysts for sunlight-driven H2 production by surface engineering to adjust the work function of photocatalyst surfaces, adsorption/desorption ability of substrates and products, and reaction activation energy barrier. Single-atom Pt-doped TiO2-x nanosheets (NSs), mainly including two facets of (001) and (101), with loading of Pt nanoparticles (NPs) at their edges (Pt/TiO2-x-SAP) are successfully prepared by an oxygen vacancy-engaged synthetic strategy. According to the theoretical simulation, the implanted single-atom Pt can change the surface work function of TiO2, which benefits electron transfer, and electrons tend to gather at Pt NPs adsorbed at (101) facet-related edges of TiO2 NSs for H2 evolution. Pt/TiO2-x-SAP exhibits ultrahigh photocatalytic performance of hydrogen evolution from dry methanol with a quantum yield of 90.8% that is ∼1385 times higher than pure TiO2-x NSs upon 365 nm light irradiation. The high H2 generation rate (607 mmol gcata-1 h-1) of Pt/TiO2-x-SAP is the basis for its potential applications in the transportation field with irradiation of UV-visible light (100 mW cm-2). Finally, lower adsorption energy for HCHO on Ti sites originated from TiO2 (001) doping single-atom Pt is responsible for high selective dehydrogenation of methanol to HCHO, and H tends to favorably gather at Pt NPs on the TiO2 (101) surface to produce H2.

A facile synthesis of sub-10 nm Ni2P/g-C3N4 photocatalytic composite with ohmic contact for clean H2-energy generation under visible light irradiation

It is very attractive to find a cheap and efficient cocatalyst for enhancing the H2 generation of graphitic carbon nitride (CN) under visible light. To achieve that, we proposed a novel two-step method to deposit sub-10 nm metallic Ni2P particles on the surface of CN sheets for a maximized interfacial contact. Characteristic results confirmed the establishment of ohmic heterojunction upon Ni2P-modification of CN, which deemed to be an effective measure to alleviate photo-charges recombination. In addition to facilitating spatial separation of charges, Ni2P could also enhance the optical properties of CN while reducing its impedance for interfacial electron shuttling. Better still, the P-end of Ni2P is highly electronegative, offering desirable H+-capturing capability for enhanced H2 generation. These give rise to an improved H2 production of Ni2P/CN composite, optimally at 645.3 μmol g−1·h−1 as compared to immeasurable H2 yielded by the pristine CN. Such photocatalytic performance is even comparable to the Pt-modified CN photocatalyst (640.6 μmol g−1·h−1). In recyclability test, a notable activity suppression of 33.17% was recorded after four reaction cycles. This can be ascribed to the pronounced photo-corrosion of the Ni2P cocatalyst during photoreaction. Nonetheless, a remarkably high H2 generation (1328.6 μmol g−1 in 3 h) was still attained at 4th cycle. This justifies the effectiveness of our synthesized Ni2P cocatalyst in enhancing H2 generation of CN under visible light irradiation.

O and S co-doping induced N-vacancy in graphitic carbon nitride towards photocatalytic peroxymonosulfate activation for sulfamethoxazole degradation

Doping-induced vacancy engineering of graphitic carbon nitride (GCN) is beneficial for bandgap modulation, efficient electronic excitation, and facilitated charge carrier migration. In this study, synthesis of oxygen and sulphur co-doped induced N vacancies (OSGCN) by the hydrothermal method was performed to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) antibiotic degradation and H2 production. The results from experimental and DFT simulation studies validate the synergistic effects of co-dopants and N-vacancies, i.e., bandgap lowering, electron-hole pairs separation, and high solar energy utilization. The substitution of sp2 N atom by O and S co-dopants causes strong delocalization of HOMO-LUMO distribution, enhancing carrier mobility, increasing reactive sites, and facilitating charge-carrier separation. Remarkably, OSGCN/PMS photocatalytic system achieved 99.4% SMX degradation efficiency and a high H2 generation rate of 548.23 μ mol g−1 h−1 within 60 min and 36 h, respectively under visible light irradiations. The SMX degradation kinetics was pseudo-first-order with retained recycling efficiency up to 4 catalytic cycles. The results of EPR and chemical scavenging experiments revealed the redox action of reactive oxidative species, wherein 1O2 was the dominant reactive species in SMX degradation. The identification of formed intermediates and the SMX stepwise degradation pathway was investigated via LC-MS analysis and DFT studies, respectively. The results from this work anticipated deepening the understanding of PMS activation by substitutional co-doping favoring N-vacancy formation in GCN lattice for improved photocatalytic activity.

Enhanced piezocatalytic activity in ion-doped SnS2 via lattice distortion engineering for BPA degradation and hydrogen production

Piezocatalysis is capable of converting mechanical vibrations into chemical energy, portraying a promising alternative technology for wastewater purification and energy regeneration. Tin disulfide (SnS2) has evoked considerable attention in piezocatalysis, yet the efficiency is still far from satisfactory due to the undesirable piezoelectricity. Herein, lattice strain engineering induced by the difference in ion sizes (Cu and Ag to Sn) was utilized for the first time to improve the piezoelectricity of SnS2 to achieve the complete removal of bisphenol A (BPA) in 30 min and a high H2 generation rate (399 μmol g−1 h−1). Mechanism analyses reveal that doping can induce S vacancies and formation of amorphous, increasing the number of surface-reaction sites. Piezoelectricity of SnS2 can be improved greatly due to lattice distortion and uneven charge distribution after doping. These synergistic effects result in elevated carriers and reactive species concentration. Impressively, Ag doping aggravates the lattice deformation due to the largest radius, exhibiting the highest piezocatalystic performance. This efficient lattice distortion engineering can serve as guideline for the development of piezocatalysts for environment remediation and production of hydrogen energy.

Interface reinforced 2D/2D heterostructure of Cu-Co oxides/FeCo hydroxides as monolithic multifunctional catalysts for rechargeable/flexible zinc-air batteries and self-powered water splitting

Elaborate engineering of heterostructure and composition to regulate the electroactivities remains a pronounced challenge. Herein, a self-supported 2D/2D heterostructure monolith is constructed by interlinked FeCo-hydroxides nanosheets tightly interlacing with aligned Cu0.76Co2.24O4 nanoplates. Due to the well-defined hierarchical nanoarrays and desirable interfacial coupling, the monolithic catalyst can guarantee the rapid charge transfer and mass transport pathways for accelerated surface kinetics, leading to manifestly improved electroactivities and stability toward trifunctional catalysis. Both experimental and theoretical calculations unravel the enriched multimetal active sites for intermediates adsorption and the synergistic interplay of the heterostructure to achieve enhanced catalytic efficiency. Consequently, the heterostructure catalyst contributes to high-performance rechargeable/flexible all-solid-stated Zn-air batteries and water electrolyzer with an ultralow potential of 1.51 V. Moreover, self-powered water splitting system driven by flexible Zn-air batteries delivers a high H2 generation rate. This cost-effective heterostructure monolith could open an intriguing avenue for advancing all-in-one films toward portable energy conversion/storage.

Facile construction of carbon doped carbon nitride tube with increased π-electron density for highly efficient hydrogen production

Carbon doping is a promising strategy to enhance the catalytic performance of carbon nitride. Herein, a microtube-shaped carbon doped carbon nitride photocatalyst with increased π-electron density is developed, which is successfully applied in water splitting under visible light irradiation. The special tubular texture and the effective π delocalization caused by carbon doping largely broaden the light absorption range, boost the separation and transfer of charge carriers. The hydrogen evolution rate of carbon doped carbon nitride is enhanced by 3.1 times than that of the pure carbon nitride. And the experimental calculations and density functional theory indicate that carbon doping plays a critical role in improving catalytic performance owing to the increased π-electron densities. The unique tubular texture provides the improved surface area and numerous active sites for carbon nitride, which benefits the adsorption of reactant molecules and improves structural stability. Meanwhile, carbon doping can control electron density, adjust the band structure to accelerate charge carrier transfer and separation rate, and finally enhance the H2 generation rate. This work sheds light on the development of carbon nitride-based photocatalysts with a high H2 generation rate.

Unveiling the role of metallic CoP@Ni2P sea-urchin-like nanojunction as a photothermal cocatalyst for enhancing the H2 generation and benzaldehyde formation over CdZnS nanoparticles

Aiming to develop a photocatalyst that can simultaneously produce valuable chemicals and clean H2 fuel for promoting the utilization efficiency of solar energy, herein, a sea-urchin-like CoP@Ni2P binary nanojunction was employed as an efficient photothermal cocatalyst to couple with zero-dimensional CdZnS (CZS) solid solution for achieving superior coordinative redox reaction. The CoP@Ni2P/CZS hybrid displayed a high solar-driven H2 generation rate of 40.92 mmol g–1 h–1 coupling with a benzaldehyde formation rate of 20.33 mmol g–1 h–1, which was 16.4 and 8.0 times higher than that of bare CZS. Furthermore, the CoP@Ni2P/CZS hybrid also achieved a high photothermal H2 production under a broad light range from 420 to 720 nm, and the H2 production reached 44.48 µmol g–1 h–1 under the 720 nm light illumination. The enhanced catalytic performance can be ascribed to that the CoP@Ni2P nanojunction with photothermal effect can speed up the separation and transport of carriers, offer more catalytic active sites, and induce an increase in temperature to optimize reaction kinetics. This study may open a facile route to design novel binary metal phosphides with dual functions in photocatalysis for the full exploitation of solar energy.