Facile Chemical Reduction Research Articles

Biomimetic joints inspired soft and hard combined 2D diamond solvent-free nanofluids with multi-layer structure for superior lubrication

The articulating joints consist of a three-layer lubricating structure, which combines soft and hard materials, including cartilage, polymer brushes, and a hydration layer. This structure leverages the synergistic effects of fluid and boundary lubrication to maintain ultra-low friction under different pressures on the same frictional surface. In this study, a biomimetic multilayer lubricating structure inspired by joint tissues is constructed using single-crystalline diamond nanosheets (SCND) as the hard phase material. Through a facile chemical reduction method and employing polydopamine (PDA) as a "bridge", a soft phase material is deposited onto the SCND surface to produce diamond composite silver nanocomposites (SCND@PDA@Ag). Subsequently, two solvent-free SCND@PDA@Ag nanofluids are prepared by grafting organic canopy substances onto the SCND@PDA@Ag surface via ionic bonds or covalent bonds, referred to as SCND@PDA@Ag-ionic bonding nanofluid and SCND@PDA@Ag-covalent bonding nanofluid, respectively. The findings reveal that the SCND@PDA@Ag-covalent bonding solvent-free nanofluid exhibits superior lubricating performance for steel/SiC contacts. The friction coefficient and wear rate for steel/SiC are significantly reduced by 93.2 % and 63.1 %, respectively, compared to dry friction, it's noteworthy that these results outperform those achieved by individual components of the lubricant. During the friction process, SCND and silver particles on the surface of SCND@PDA@Ag-covalent bonding solvent-free nanofluid work together to enhance lubrication synergistically. Furthermore, silver particles on the surface of SCND are released and fill into the worn surface, providing a repairing effect. This study highlights that the design of soft-hard multilayer structures offers a novel approach for researching nanocomposite materials in the field of tribology.

Multifunctional silver nanoparticles decorated N, S co-doped graphene as a sensitive colorimetric probe for L-cysteine detection and as an antibacterial agent

The fabrication of structured nanocomposites possessing dual applications have always attracted great research attention, especially in the fields of biomolecule detection and as antibacterial agents. In the current study, silver nanoparticles grafted on N, S co-doped graphene (Ag-NSG) were synthesized using a simple and facile chemical reduction method. The synthesized nanocomposite was employed as a colorimetric probe for the detection of L-cysteine (L-cys) in chickpea (Cicer arietinum L.) and as an antibacterial agent against Gram-positive positive (S. aureus) and Gram-negative (E. coli) bacteria. Ag-NSG exhibited a highly cordant recovery of 98.4 % for the different chickpea samples, signifying an outstanding selectivity of the proposed probe towards the target analyte. The antibacterial investigation was carried out employing the agar well diffusion method, by measuring the zone of inhibition (ZOI), under different dosages of the synthesized nanocomposite. The zone of inhibitions increased with increasing concentrations and the highest zone obtained was 30.6 ± 1.2 mm for S. aureus and 25.3 ± 0.3 mm for E. coli.

Li-Sn Alloyed Layer Containing Artificial SEI on Li-Metal Anode for Superior Lithium Metal Batteries: Development and Understanding of Anode/Electrolyte Interfacial Phenomena

Modern civilization and cutting-edge technologies and tools are highly dependent on energy storage devices and demand efficient and long-lasting high-energy-density storage devices. Lithium metal batteries have surpassed their competitors concerning energy density due to their inherent high specific capacity (3860 mAh/g) and the lowest electrochemical potential (-3.04 V vs. standard hydrogen electrode), proving to be one of the most favorable energy storage devices for smart and mobile gadgets, electric automobiles, grid storage, etc. However, safety-threatening and performance-decay challenges associated with lithium metal anodes, such as lithium dendrite formation, uncontrolled parasitic reactions between Li-metal and electrolyte, low coulombic efficiency, dead Li-formation, etc., restrict its employment in practical batteries. The root cause of the dendrite formation is poor Li-ion conductivity of bulk lithium metal, which results in an uneven electric field distribution, leading to non-uniform Li deposition/stripping upon repeated charge/discharge. Herein, a facile chemical reduction process is being opted to fabricate a highly Li-ion diffusive Li-Sn-based artificial SEI layer on the lithium metal surface to prevail over the above-mentioned issues. Therefore, upon careful concentration investigation of reactants, 25 mM precursor concentration (SnCl4 in EC: DMC in 1:1 volume ration) demonstrated the best electrochemical performance, revealing a cumulative capacity of over 700 mAh/cm2 at a current density of 1 mA/cm2 for 1 h in a symmetric cell. Physical characterizations (XRD and SEM-EDS) showed a thin layer containing Li-Sn alloys along with LiCl formed at the lithium metal surface. Possessing high Li-ion diffusivity, Li-Sn alloyed hybrid anode illustrated a gradual decrease in the charge transfer resistance on increasing the concentration, thus, lower overpotential in symmetric cells, in contrast to pristine Li-metal. However, an increase in the electrical resistance has been observed on increasing the precursor concentration due to the presence of the insulating LiCl phase in the protective layer. Moreover, in-situ optical microscopy demonstrated more uniform and on-surface Li-deposition for the hybrid electrode, whereas mossy and dendritic growth on bare Li-metal. Full cells prepared with Li-Sn alloyed anode against NMC532 cathode illustrated stable cycling up to 150 cycles; contrastingly, the cell with pristine Li-metal showed a drastic capacity fade just after 100 cycles, demonstrating the inclination towards safer lithium metal batteries.

Effect of graphite concentration on the electrochemical performance of a novel α-MnO2-expanded graphite-PVDF composite cathode material based on FTO substrate

A facile chemical reduction method is employed for the synthesis of α-MnO2 followed by ultrasonication with synthetic graphite and poly (vinylidene pyrrolidone) PVDF for the development of α-MnO2-expanded graphite-PVDF (MGP) composite. Known masses of MGP composite are drop-casted on a fluorine-doped tin oxide (FTO) conducting glass substrate for the fabrication of composite electrodes to use as the cathode. The compositional effects of various weight percentages of graphite on the electrochemical performance of the MGP composite are studied. The increase in graphite’s weight percentage is always accompanied by an equal reduction in the weight of MnO2 by maintaining a constant amount of PVDF. We demonstrate a maximum electrochemical performance for the composite containing 80% MnO2, 10% expanded graphite, and 10% PVDF, further increases in graphite concentration (reduction in that of MnO2) have detrimental effects on the performance. The basis characterisation of the composite is carried out using XRD, FTIR, UV–vis, AFM, and SEM and the electrochemical studies are done using CV, GCD and EIS. We observe both faradaic and non-faradaic charge storage mechanisms in the composite samples with a 35% capacitive contribution and a 65% diffusive contribution to the total capacitance. Moreover, the composite electrode demonstrates a maximum specific capacitance of 358 F g−1 at 10 mV s−1 with an outstanding power density of 2.8 KW Kg−1.

Synergism of carbonaceous additives in engineering of the supercapacitive performance of α-and λ-phases of manganese oxide

Owing to the presence of valence shells for charge transfer, a high theoretical specific capacitance, and variable redox properties, MnO2 appears as a promising agent in the realm of energy storage. Crystallographic structures of manganese oxide (MnO2), a transition metal oxide, play a crucial role in determining its capacitive behavior by controlling the ion intercalation and double-layer formation. In this work, two different phases of MnO2 were synthesized using the facile chemical reduction method and biological method, say α-MnO2 and λ-MnO2. The phases were incorporated with different carbonaceous additives including GO and CNT while maintaining a constant weight ratio of 8:1:1 between active materials (MnO2), additive, and PVDF binder. Among different composites formed, the best electrode performance is demonstrated by λ-MnO2/CNT/PVDF composite with an excellent specific capacitance of 356 F/g at a scan rate of 1 A/g. Moreover, the best-performing electrodes are investigated with a symmetrical two-electrode system yielding a wide potential window of 1.8V with an outstanding power density of 13.5 KW/Kg at 5 A/g and an energy density of 53.78 Wh/Kg at 1A/g having a specific capacitance of 190 F/g.

Oxygen-deficient AgIO3 for efficiently photodegrading organic contaminants under natural sunlight

Defect engineering is regarded as an effective strategy to boost the photo-activity of photocatalysts for organic contaminants removal. In this work, abundant surface oxygen vacancies (Ov) are created on AgIO3 microsheets (AgIO3-OV) by a facile and controllable hydrogen chemical reduction approach. The introduction of surface Ov on AgIO3 broadens the photo-absorption region from ultraviolet to visible light, accelerates the photoinduced charges separation and migration, and also activates the formation of superoxide radicals (•O2−). The AgIO3-OV possesses an outstanding degradation rate constant of 0.035 min−1, for photocatalytic degrading methyl orange (MO) under illumination of natural sunlight with a light intensity is 50 mW/cm2, which is 7 and 3.5 times that of the pristine AgIO3 and C–AgIO3 (AgIO3 is calcined in air without generating Ov). In addition, the AgIO3-OV also exhibit considerable photoactivity for degrading other diverse organic contaminants, including azo dye (rhodamine B (RhB)), antibiotics (sulflsoxazole (SOX), norfloxacin (NOR), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)), and even the mixture of organic contaminants (MO-RhB and CTC-OFX). After natural sunlight illumination for 50 min, 41.4% of total organic carbon (TOC) for MO-RhB mixed solution can be decreased over AgIO3-OV. In a broad range of solution pH from 3 to 11 or diverse water bodies of MO solution, AgIO3-OV exhibits attractive activity for decomposing MO. The MO photo-degradation process and mechanism over AgIO3-OV under natural sunlight irradiation has been systemically investigated and proposed. The toxicities of MO and its degradation intermediates over AgIO3-OV are compared using Toxicity Estimation Software (T.E.S.T.). Moreover, the non-toxicity of both AgIO3-OV catalyst and treated antibiotic solution (CTC-OFX mixture) are confirmed by E. coli DH5a cultivation test, supporting the feasibility of AgIO3-OV catalyst to treat organic contaminants in real water under natural sunlight illumination.

A Facile Chemical Reduction Approach of Li–Sn Modified Li Anode for Dendrite Suppression

Lithium dendrites are among the most significant threats associated with the practical application of lithium metal anode in lithium batteries. Lithium dendrites are caused by the slow Li‐ion diffusivity in the bulk lithium, which results in a non‐uniform electric field‐cum‐uneven Li plating/stripping at the electrode/electrolyte interface over prolonged cycling. Herein, a facile chemical reduction method is utilized to construct a Li‐ion diffusive Li–Sn protective layer on the electrolyte‐exposed surface of lithium metal to overcome the aforementioned challenge. A systematic study on the SnCl4 precursor concentration variation demonstrated that 25 mM SnCl4 concentration is the most effective and displays a cumulative areal capacity beyond 700 mAh cm−2 at 1 mA cm−2 for 1 h. Moreover, it exhibits superior cumulative capacities than bare Li metal at higher current densities of 2 and 3 mA cm−2. In situ optical microscopy reveals more uniform lithium deposition on the Li–Sn‐modified electrode, while mossy and dendritic lithium growth is observed on the bare lithium electrode. Full cells fabricated with Li–Sn modified anode and NMC532 cathode exhibited 83% capacity retention after 150 cycles, outperforming bare Li‐containing cells, which shows a catastrophic decay post 100 cycles, illustrating the propensity for safer Li metal batteries with Li–Sn modified anode.

AgCo bimetallic cocatalyst modified g-C3N4 for improving photocatalytic hydrogen evolution

Bimetallic AgCo/g-C3N4 photocatalysts were successfully prepared by a facile chemical reduction method and used to investigate their photocatalytic H2 production performance. Bimetallic AgCo as a cocatalyst can be well matched with g-C3N4, which is beneficial for increasing the number of active reaction sites and narrowing the band gap. A possible photocatalytic mechanism was explored by XRD, FTIR, SEM, TEM, UV–vis DRS, BET, and PL characterization. The photocatalytic H2 production activity of the optimal 5%AgCo/g-C3N4 photocatalyst reached 12994.2 μmoL/g, which was 54.7 times higher than g-C3N4. Owing to the close interfacial contact between bimetallic AgCo and g-C3N4, the transfer distance was shortened, and the photogenerated electron and hole pairs were effectively separated. This study provides a new strategy for the synthesis of excellent H2 production photocatalysts using bimetallic nanoparticles.

Efficient hydrogen production via overall water splitting using CuO/ZnO decorated reduced graphene oxide as bifunctional electrocatalyst

Conjunction of ‘n’ and ‘p’-type materials have gained considerable attention for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) as potential substitutions to noble metal based nanomaterials. Current work has been designed to synthesize mixed-phase nanocomposite (NC) based on copper (CuO) and zinc oxide (ZnO) nanowires (NWs) and reduced graphene oxide (rGO). A facile chemical reduction method was used for the preparation of NWs, rGO were prepared using modified Hummer's method and lastly CuO/ZnO NWs were grafted on rGO to fabricate NC (CuO/ZnO@rGO) by wet-chemical approach. Characterization techniques were employed to confirm the formation as well as different morphological features of NC. Noticeable D and G bands in Raman spectrum confirmed the formation of NC and EDAX confirmed the presence of C, O, Zn and Cu. XRD analysis has confirmed hexagonal wurtzite structure of NC with a crystallite size of 10.1392 nm. Synthesized material was then investigated for OER and HER in an alkaline medium. As electrocatalyst, NC exhibited overpotential (OP) of 1.678 V to accomplish 10 mA/cm−2 current density (J) in OER and −358 mV (10 mA/cm−2) for HER respectively. Tafel curves of CuO/ZnO@rGO in OER (42 mV dec−1) and HER (270 mV dec−1) were found similar enough to others studies. Proliferated electrochemical activities are responsible for such a lower OP and Tafel slope values that may be due to electronic couplings of copper and zinc, or the homogenous distribution of both the metal oxides which gives polydispersity in their structure as confirmed by SEM images. Promising results of the current study indicated high-performance of synthesized electrocatalyst. Further studies can be designed to evaluate the efficiency of different combinations of noble/non-noble metals or metal oxides with rGO as potential candidate for electrochemical reactions.

Controlled Growth of Silver Nanoparticles on Cotton Substrate for Enhanced SERS, Catalytic, and Antibacterial Performance

AbstractIn this study, we report the growth of surfactant‐free silver nanoparticles (NPs) on cotton through a facile chemical reduction method, iteratively applied to gradually increase and control the concentration of silver NPs. Our substrates showed enhanced performance in surface enhanced Raman spectroscopy (SERS), catalytic, and antibacterial properties, all attributable to the high concentration of NPs on the cotton and their surfactant‐free nature. While the antibacterial properties improve with increasing growth cycles, SERS and catalytic properties first increase from the first to fourth growth cycles and then decrease for the fifth growth cycle. For substrate with optimum deposition for SERS, rhodamine 6G (R6G) analyte down to nanomolar concentrations were detectable, with a linear correlation of intensity versus concentration and exhibit excellent uniformity in the SERS signal. Furthermore, the catalytic activity of our substrates against the degradation of methyl orange (MO) was impressive with a rate constant of 0.0866 min−1 for the first growth cycle, which increased by ~3.4‐fold to 0.2979 min−1 for the fourth growth cycle. Finally, the substrates showed excellent antibacterial activity towards both Gram‐negative (E. coli) and Gram‐positive (S. aureus) bacteria. For both bacteria, the zone of inhibition increased with increasing growth cycles.

Robust and multifunctional MXene/rGO composite aerogels toward highly efficient solar-driven interfacial evaporation and wastewater treatment

Given the ever-growing global water resource crisis, exploiting multifunctional materials featuring with high interfacial solar steam generation efficiency and good purification capability to achieving seawater desalination and wastewater treatment simultaneously are highly desired, yet it still remains a huge challenge to date. Herein, robust and multifunctional MXene/rGO (MRGA) and polydopamine & chitosan @ MRGA (CS&PDA@MRGA, CPM) three-dimensional composite aerogels with distinct interconnected cellular architecture were developed via a facile ice template-assisted chemical reduction self-assembly technology and subsequent sequential deposition modification. Due to the favorable graphene oxide-assisted assembly behavior, the resultant aerogels displayed a desirable mechanical robustness along with an excellent lightweight property. Benefiting from the strong electrostatic interaction deriving from aerogel surface moieties and dye molecules, MRGA-12 exhibited a prominent adsorption capability towards various dyes and achieved a superb adsorption capacity of up to 396.05 mg/g for malachite green (MG). Moreover, by virtue of the synergistic effect between the intentionally regulated low reduction degree of rGO and the integration of PDA and CS, CPM-12 achieved a dramatically reduced evaporation enthalpy of water from 2256 to 1617.18 J/g. Accordingly, this distinct feature resulted in an extraordinary solar-driven interfacial evaporation performance with a remarkable evaporation rate of 1.86 kg/m2/h and a high evaporation efficiency of 83.28 % under 1 sun illumination. Therefore, together with the terrific oil/water separation capability, these novel MXene-based aerogels hold a great potential for high-performance solar-driven interfacial evaporation and wastewater treatment.

Plasmon-enhanced CO2 electroreduction on copper, silver, and copper-silver nano-catalysts

CO2 electrochemical reduction (CO2ER) allows the conversion of CO2 into fuels and chemicals. Copper is the only known catalyst that converts CO2 into hydrocarbon products but is hindered poor selectivity and stability. Cu-based bimetallic particles have shown to improve the selectivity and stability of the catalysts. This work reports a novel study in the use of a broad-range light source to induce the plasmonic effect in Cu, Ag and Cu-Ag bimetallic nanoparticle catalysts for CO2ER. Active Cu100-xAgx (x = 0, 50, 60, 75, 85, 100 at.%) catalysts were synthesized using a facile chemical reduction and compared to commercial counterparts. The catalytic activity of the particles was correlated with detailed physicochemical characterizations. The synthesized particles were found to be active catalysts for CO2ER, with improved electro-catalytic activities exhibited by Cu85Ag15, Cu60Ag40 and Cu syntheses in respective order. All nanoparticles demonstrated increases in the catalytic activity ranging between 15 and 26 % under white light illumination, attributed to plasmonic promotion using a broad visible wavelength range cold halogen lamp for the first time on CO2ER. The best plasmonic promotion of 26 % was observed in the CuAg commercial alloy. Meanwhile, the best promotion of the synthesized bimetallic particles was of 18 % found in the Cu60Ag40 catalyst. Additionally, improved electrochemical and plasmonic stability was observed with the use of the Cu-Ag bimetallic synthesized structures compared to monometallic Cu.

FeCoNiMgB high-entropy boride powder with a fluffy cotton structure and enhanced activity in the oxygen evolution reaction

Exploring efficient, low-cost electrocatalysts is critical for improving the efficiency of water splitting reactions. Noble-metal-based oxides exhibit high activities in the oxygen evolution reaction (OER). However, their high cost and the lack of natural resources hinder their practical application. Therefore, in this study, we successfully synthesized an FeCoNiMgB high-entropy boride powder via a facile chemical reduction method for use as an OER catalyst in an alkaline medium. The FeCoNiMgB powder, with an ultrathin fluffy cotton structure, exhibited an excellent OER catalytic performance, affording an overpotential of 268 mV at a current density of 10 mA/cm2 and a low Tafel slope of 42.9 mV/dec; this performance was superior to those of FeCoNiB, FeNiMgB, CoNiMgB, FeCoMgB, and commercial RuO2. The FeCoNiMgB powder also displayed remarkably stable catalytic properties for >72 h with no clear evidence of degradation. Finally, using theoretical calculations, the excellent OER performance of FeCoNiMgB was verified in terms of its adsorption and charge transfer energies and covalence. The performance and stability of FeCoNiMgB were equivalent or superior to those of several nanostructured catalysts, and thus, this study provided valuable insight into the design of efficient high-entropy boride materials.

Rapid chemical reduction synthesis of copper nanoclusters with blue fluorescence for highly sensitive detection of furazolidone.

Tannic acid (TA), as a stabilizing agent, was successfully utilized to establish blue-emitting copper nanoclusters (TA-Cu NCs) on the basis of a facile chemical reduction preparation method. Characterization results proved successful synthesis of TA-Cu NCs with uniform size and excellent stability. TA-Cu NCs exhibited a blue emission wavelength at 431 nm when excited at 364 nm. Interestingly, the as-prepared TA-Cu NCs were selectively quenched by furazolidone based on static quenching. In addition, this analysis platform for furazolidone detection had an excellent linear range from 0.5 to 120 μM with a detection limit of 0.074 μM (S/N = 3). Furthermore, the accuracy of this sensing method was successfully confirmed by detecting furazolidone in bovine serum samples, indicating that TA-Cu NCs had bright application prospects.

Morphology dependent EMI shielding performance of Ag-Ni core-shell nanowires

The proposed work reports a facile chemical reduction method for synthesizing the hierarchical silver-nickel core-shell nanowire structures with controllable morphologies by varying the Ag concentration. The growth of Ni shells around the Ag core to make thorny and smooth Ag-Ni core-shell nanowires is studied for addressing electromagnetic interference (EMI). The synthesized Ag-Ni nanowires show better EMI shielding effectiveness (SE) than Ni nanowires with much-improved absorption loss (SEA). Due to high electrical conductivity (8630 S cm−1), magnetic permeability (44.1 emu/g), and heterojunction core-shell interfaces, the bimetallic nanowires flakes exhibit exceptional average EMI SE of 90.5 dB in the X-band frequency range (8–12 GHz) with a thickness of 0.11 mm, taking specific EMI SE to 822.72 dB/mm. In addition, the EMI shielding performance of the smooth Ag-Ni nanowires showed a 45% enhancement in SEA with marginal change in reflection loss (SER) compared to the thorny ones, indicating high absorption of EM waves. The unique core-shell nanowires with high aspect ratio with tunable physical properties can be ideal candidates for futuristic applications in microwave absorption and electromagnetic interference shielding.

Tailoring iridium-palladium nanoparticles with Ir-rich skin: a highly durable anode electrocatalyst for acidic water electrolysis via a facile microwave-assisted chemical reduction method.

Electrochemical water splitting under acidic conditions is a clean way towards producing hydrogen fuels. The slow kinetics of the oxygen evolution reaction (OER) at the anode is currently a bottleneck for commercial acceptance of this technology. Therefore, arriving at more efficient and sustainable OER electrocatalysts is highly desirable. We here demonstrate the synthesis of iridium-palladium (IrPd) alloy nanoparticles (2-5 nm) with variable average composition (Ir : Pd = 1 : 0, 1 : 1, 1 : 3, 1 : 6, 1 : 9 and 0 : 1) using a facile one-pot microwave-assisted chemical reduction method. The IrPd nanoparticles show structure- and composition-dependent OER performance in acidic media. Utilizing different reduction strengths and precursor ratios, successful alloy catalysts were prepared with Ir-rich skin and sublayers of different Pd compositions. Their structures were revealed using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen underpotential deposition (Hupd) studies. It turned out that (1) the alloy OER catalyst also has a high electrochemically active surface area for hydrogen adsorption/desorption, (2) the OER performance is strongly dependent on the surface Ir contribution and (3) the intact Ir skin is essential for electrocatalyst stability.

Rational synthesis of 3D coral-like ZnCo2O4 nanoclusters with abundant oxygen vacancies for high-performance supercapacitors.

Transition metal oxides with high theoretical capacitance are regarded as desired electrode materials for supercapacitors, however, the poor conductivity and sluggish charge transfer kinetics constrain their electrochemical performance. The three-dimensional (3D) coral-like ZnCo2O4 nanomaterials with abundant oxygen vacancies were synthesized through a facile hydrothermal method and chemical reduction approach. The introduced oxygen vacancies can provide more active sites and lower the energy barrier, thereby facilitating the kinetics of surface reactions. Furthermore, the abundant oxygen vacancies in metal oxides can function as shallow donors to facilitate charge carrier diffusion, resulting in a faster ion diffusion rate and superior electrochemical conductivity. The electrochemical performance of ZnCo2O4 was optimized by the introduction of oxygen vacancies. The ZnCo2O4 nanoclusters, reduced by 0.5 M NaBH4 (ZnCo2O4-0.5), exhibit a specific capacitance of 2685.7 F g-1 at 1 A g-1, which is nearly twice that of the pristine ZnCo2O4 (1525.7 F g-1 at 1 A g-1). The ZnCo2O4-0.5 exhibits an excellent rate capacity (81.9% capacitance retention at 10 A g-1) and a long cycling stability (72.6% specific capacitance retention after 10 000 cycles at 3 A g-1). Furthermore, the asymmetric supercapacitor (ASC, ZnCo2O4-0.5 nanoclusters//active carbon) delivers a maximum energy density of 50.2 W h kg-1 at the power density of 493.7 W kg-1 and an excellent cycling stability (75.3% capacitance retention after 3000 cycles at 2 A g-1), surpassing the majority of previously reported ZnCo2O4-based supercapacitors. This work is important for revealing the pivotal role of implementing the defect engineering regulation strategy in achieving optimization of both electrochemical activity and conductivity.

Ultra-small water-soluble fluorescent copper nanoclusters for p-nitrophenol detection.

Due to the widespread application of p-nitrophenol (p-NP) across various industries, particularly in the pharmaceutical and chemical sectors, it has emerged as a significant environmental contaminant in both soil and water ecosystems. The development of swift and sensitive detection platforms for p-NP is therefore demanding. Herein, a fluorescence sensor based on ultra-small copper nanoclusters with exterior glutathione ligands determined by electrospray ionization mass spectrometry (ESI-MS) as [Cu14(SG)12]+ (denoted as Cu-SG NCs) has been prepared in high efficiency, and shown high selectivity for p-NP detection. The Cu-SG NCs, synthesized via a facile one-pot chemical reduction technique, exhibit emission maxima at 620 nm. Notably, the introduction of p-NP into the nanocluster system causes a significant quenching of the Cu-SG NCs fluorescence. The quenching phenomenon arises predominantly as a result of the inner filter effect (IFE), which stems from the substantial overlap between the UV-Vis absorption spectrum of p-NP and the excitation wavelength of Cu-SG NCs. The developed fluorescence sensor platform demonstrates a wide determination range for p-NP, ranging from 0.04 to 2000 µM, with a detection limit of 30 nM. Additionally, the sensor efficacy was successfully validated in the analysis of actual water samples. The ease of synthesis, excellent optical properties, and low toxicity of Cu-SG NCs represent significant advantages over the reported noble metal nanomaterials and is highly promising for future practical applications.

Full-spectrum Bi@SrTiO3 for bi-directional promotion effects on photocatalytic redox reaction: Insight into intermediates and mechanism

The development of full-spectrum photocatalysts active in the near-infrared (NIR) region has gained increasing attention for deleterious pollutant removal. The integration of plasmonic metals with semiconductors is an effective way to widen the light response range of photocatalysts due to the strong light absorption and fast plasmonic energy transfer of the localized surface plasmon resonance (LSPR). In this work, the full-spectrum responsive Bi@SrTiO3 was prepared via facile solvothermal chemical reduction. The optimal Bi@SrTiO3 achieves exceptional photocatalytic Cr(VI) reduction efficiency and tetracycline degradation, realizing bi-directional promotion effects on redox reaction. According to density functional theory (DFT) simulations, the extraordinary photocatalytic performance is attributed to the tunable built-in electric field (IEF) of the Ohmic contact. The favorable adaptability in real water and high stability of BSTO-25 were proved by experimental results. And the possible photocatalytic mechanism was proposed based on theoretical calculation and experimental results. Furthermore, the non-toxicity of the BSTO-25 was evaluated by E.coli cultivation, which further proves the feasibility of treating wastewater with BSTO-25. This work provides a new perspective on constructing full-spectrum-driven photocatalysts for applications dealing with environmental remediation.

Defect engineering of hollow porous N, S co-doped carbon spheres-derived materials for high-performance hybrid supercapacitors

Defect engineering, such as introducing heteroatoms and vacancies into the electrode materials, provides a feasible strategy for boosting the electrochemical characteristics of hybrid supercapacitors. In this work, hollow N, S co-doped carbon (HNSC) spheres with high specific surface area are fabricated through the carbonization-etching process. Thanks to the unique porous architecture and multiple heteroatoms doping, the obtained HNSC electrode achieves an excellent capacitance of 330.4 F g−1 at 1 A g−1 and superior capacitance retention of 97 % after 10,000 cycles in 6 M KOH. Subsequently, the Co3S4 nanoparticles with controllable sulfur vacancies (Vs-Co3S4) are homogeneously deposited on the HNSC skeleton by a facile chemical reduction strategy. The fabricated Vs-Co3S4/HNSC cathode exhibits a compelling electrochemical capacity of 497.2 C g−1 at 1 A g−1 and a prominent cycle life of 98.1 % after 10,000 cycles in 6 M KOH. Noticeably, benefiting from the defects regulation and unique structures of HNSC and Vs-Co3S4/HNSC, the constructed hybrid supercapacitor of VS-Co3S4/HNSC//HNSC reaches a marvelous energy density of 71.4 Wh kg−1 at 925.3 W kg−1 with only 8.1 % capacity loss within 15,000 cycles at 10 A g−1. Such eminent electrochemical features inspire the rational design of advanced defect-modulated electrode materials for energy storage applications.