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Solid-phase hot-pressing of POMs-ZIFs precursor and derived phosphide for overall water splitting
摘要： A facile solid-phase hot-pressing method was applied to prepare bimetallic phosphides on carbon cloth without binder as efficient electrocatalysts for water splitting. High-performance electrocatalyst with high performance for both hydrogen and oxygen evolution reaction is attracting considerable attention in recent years. However, most electrocatalysts are powders and require to deposit on conductive substrates with binders, leading to complicated steps and hindering the improvement of long-term stability. This work exhibits a solid-phase hot-pressing method to prepare polyoxometalates based zeolitic imidazolate frameworks (POMs-ZIFs) precursor on carbon cloth (CC) rapidly and mildly. After phosphidation treatment, nitrogen-doped graphitic carbon layers coated phosphide on CC (CoP/MoP@NC/CC) is synthesized. CoP/MoP@NC/CC has excellent electrocatalytic performance for water splitting due to the synergistic effect of CoP, MoP and as-formed oxide/hydroxide layers. It shows the low overpotentials of 94 mV for HER and 270 mV for OER at the current density of 10 mA cm-2 in alkaline medium, which is superior to most of the reported phosphide-based electrocatalysts. Notably, the ultra-high current density of 1000 mA cm-2 can be reached at the overpotentials of only 475 mV for HER and 657 mV for OER. As both cathode and anode for overall water splitting, CoP/MoP@NC can achieve the current density of 50 mA cm-2 at the cell voltage of 1.71 V. The solid-phase hot-pressing method ensures the tight and uniform growth of the fast nucleating and stable materials on substrate and applies for more electrochemical reactions.
关键词： phosphide,hot-pressing,HER,OER,metal-organic framework
更新于2025-09-23 15:23:52
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Operando observation of chemical transformations of iridium oxide during photoelectrochemical water oxidation
摘要： Iridium oxide is one of the few catalysts capable of catalyzing the oxygen evolution reaction (OER) in both acidic and basic conditions. Understanding the mechanism of IrOx under realistic photoelectrochemical conditions is important for the development of integrated water splitting systems. Herein, we have developed a highly efficient OER photoanode in pH 1 aqueous solutions based on a sputtered IrOx film and a p+n-Si light absorber, interfaced with sputtered Au layer. Operando high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD XAS) was employed to monitor the oxidation state changes of IrOx during both electrochemical and photoelectrochemical (PEC) water oxidation reactions in pH 1 aqueous solutions. We observed a gradual increase of the average oxidation state of Ir with increasing anodic potential in the pre-catalytic region, followed by a reduction of Ir under O2 evolution conditions. Consistent results were obtained on dark anodes and illuminated photoanodes. However, when the thickness of IrO2 was increased to 2 and 3 nm, the spectral changes became much less pronounced and the reduction of Ir oxidation state after the OER onset was not observed. This is due to the lower surface to bulk ratio, where lattice oxygen sites in the bulk are not accessible for the formation of hydroxide. More generally, the operando method developed here can be extended to other materials, thereby providing a powerful tool for mechanism discovery and an enabling capability for catalyst design.
关键词： oxygen evolution reaction (OER),electrochemical and photoelectrochemical (PEC),high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD XAS),iridium oxide,Operando method
更新于2025-09-23 15:23:52
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One Dimensional CdS Nanotube vs CdS Bulk Structure for Photocatalytic Water Splitting: Role of Dimensionality
摘要： Using the state-of-the-art density functional theoretical calculations, we have modelled a facetted CdS nanotube (NT) catalyst for photocatalytic water splitting. The overall photocatalytic activity of the CdS photocatalyst has been predicted based on the electronic structures, band edge alignment, and overpotential study. For comparisons, we have also investigated the water spilitting process over the CdS bulk structure. The band edge alignment along with oxygen evolution reaction/hydrogen evolution reaction (OER/HER) mechanism studies help us to find out the effective overpotential for the overall water splitting on these surfaces. Our study shows that CdS NT has highly stabilized valence band edge compared to that in the CdS bulk due to strong p-d mixing. Such highly stabilized valence band edge is important for the hole-transfer process and reduces the risk of electron-hole recombination. Such nanotube requires less overpotential for water oxidation reaction than the periodic CdS. All these suggest that the efficiency of water oxidation/reduction process further improves in CdS as we reduce its dimensionality. More importantly, we report here that there are two factors, which makes CdS nanotube as a better photocatalyst material compared to its bulk counterpart. Furthermore, the stabilized valence band edge is good for their photostability too as bulk CdS suffers from photostability.
关键词： photocatalysis,HER,CdS nanotube,OER,electron-hole recombination
更新于2025-09-23 15:21:01
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High-Performance Silicon Photoanode Enabled by Oxygen Vacancy Modulation on NiOOH Electrocatalyst for Water Oxidation
摘要： Silicon (Si) is an attractive photoanode material for photoelectrochemical (PEC) water splitting. However, Si photoanode is highly challenging due to its poor stability and catalytic inactivity toward oxygen evolution reaction (OER). Integration of highly active electrocatalysts with Si photoanodes has been considered as an effective strategy to improve OER performance through accelerates reaction kinetics and inhibits Si photocorrosion. In this work, ultra-small NiFe nanoparticles are deposited onto n-Si/Ni/NiOOH surface to improve the activity and stability of Si photoanode by engineering the electrocatalyst and Si interface. Ultra-small NiFe can introduce oxygen vacancies via modulating the local electronic structure of Ni hosts in NiOOH electrocatalyst for fast charge separation and transfer. Besides, NiFe nanoparticles also can serve as co-catalyst exposure more active sites and as protection layer prevents Si photocorrosion. The as-prepared n-Si/Ni/NiOOH/NiFe photoanode exhibits excellent OER activity with an onset potential of 1.0 V versus reversible hydrogen electrode (RHE) and a photocurrent density of ～25.2 mA cm-2 at 1.23 V versus RHE. This work provides a promising approach to design high-performance Si photoanodes by surface electrocatalyst engineering.
关键词： photoelectrochemical water splitting,oxygen vacancies,OER activity,NiFe nanoparticles,Silicon photoanode
更新于2025-09-23 15:19:57
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Laser‐Ablation Produced Cobalt‐Nickel Phosphate with High‐ValenceNickel Ions as Active Catalyst for Oxygen Evolution Reaction
摘要： Cost-effective, highly efficient and stable non-noble metal-based catalysts for oxygen evolution reaction (OER) are very crucial on energy storage and conversion. Here, we report an amorphous cobalt-nickel phosphate (CoNiPO4) containing considerable amount of high-valence Ni3+ specie as an efficient electrocatalyst for OER in alkaline solution. The catalyst was converted from Co-doped Ni2P through pulsed laser ablation in liquid (PLAL) and exhibits a large specific surface area of 162.5 m2/g and a low overpotential of 238 mV at 10 mA/cm2 with a Tafel slope of 46 mV/dec, being much lower than those of commercial RuO2 and IrO2. Our work demonstrates that PLAL is a powerful technology for generating amorphous CoNiPO4 with high-valence Ni3+, thus paving a new way towards highly effective OER catalysts.
关键词： OER,high valence state,cobalt-nickel phosphate,Pulsed laser ablation in liquid
更新于2025-09-12 10:27:22
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A New Class of Zn <sub/>1</sub><i> <sub/>-x</sub></i> Fe <i> <sub/>x</sub></i> -Oxyselenide and Zn <sub/>1-</sub><i> <sub/>x</sub></i> Fe <i> <sub/>x</sub></i> -LDH Nanostructured Material with Remarkable Bifunctional Oxygen and Hydrogen Evolution Electrocatalytic Activities for Overall Water Splitting
摘要： The scalable and cost-effective H2 fuel production via electrolysis demands an efficient earth-abundant oxygen and hydrogen evolution reaction (OER, and HER, respectively) catalysts. In this work, for the first time, the synthesis of a sheet-like Zn1-xFex–oxyselenide and Zn1-xFex–LDH on Ni-foam is reported. The hydrothermally synthesized Zn1-xFex–LDH/Ni-foam is successfully converted into Zn1-xFex–oxyselenide/Ni-foam through an ethylene glycol-assisted solvothermal method. The anionic regulation of electrocatalysts modulates the electronic properties, and thereby augments the electrocatalytic activities. The as-prepared Zn1-xFex–LDH/Ni-foam shows very low OER and HER overpotentials of 263 mV at a current density of 20 mA cm?2 and 221 mV at 10 mA cm?2, respectively. Interestingly, this OER overpotential is decreased to 256 mV after selenization and the HER overpotential of Zn1-xFex–oxyselenide/Ni-foam is decreased from 238 to 202 mV at 10 mA cm?2 after a stability test. Thus, the Zn1-xFex–oxyselenide/Ni–foam shows superior bifunctional catalytic activities and excellent durability at a very high current density of 50 mA cm?2. More importantly, when the Zn1-xFex–oxyselenide/Ni-foam is used as the anode and cathode in an electrolyzer for overall water splitting, Zn1-xFex–oxyselenide/Ni-foam(+)∥Zn1-xFex–oxyselenide/Ni-foam(-) shows an appealing potential of 1.62 V at 10 mA cm?2. The anionic doping/substitution methodology is new and serves as an effective strategy to develop highly efficient bifunctional electrocatalysts.
关键词： Zn1-xFex–oxyselenide,Zn1-xFex–LDH,overall water splitting,HER,OER
更新于2025-09-10 09:29:36
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Plasmon-Enhanced Electrocatalytic Properties of Rationally Designed Hybrid Nanostructures at a Catalytic Interface
摘要： In recent years, a promising role of plasmonic metal nanoparticles (NPs) has been demonstrated toward an improvement of the catalytic efficiency of well-designed hybrid electrocatalysts. In particular, the coupling of plasmonic functionality with the metal-based core–shell architectures in plasmon-enhanced electrocatalysis provides a sustainable route to improve the catalytic performances of the catalysts. Herein, the rationally designed AuNPs wrapped with reduced graphene oxide (rGO) spacer along with PdNPs (AuNP@rGO@Pd) as the final composite are reported. The rGO is proposed to promote the reduction of PdO, greatly enhance the conductivity, and catalytic activity of these nanohybrid structures. The plasmon-enhanced electrocatalytic performance of optimized AuNP@rGO(1)@Pd exhibits an ≈1.9- and 1.1-fold enhanced activity for the hydrogen evolution reaction and oxygen evolution reaction, respectively. The final composite also exhibits a superior stability up to 10 000 s compared with the commercial Pd/C. The mechanism of the enhanced catalytic performance is monitored through in situ X-ray absorption spectroscopy by observing the generated electron density under light irradiation. The results demonstrate that the energetic charge carriers are concentrated in the incorporated PdNPs, allowing higher catalytic performances for the overall water-splitting reaction. The conclusions herein drawn are expected to shed light on upcoming plasmon-induced electrocatalytic studies with analogous hybrid nanoarchitectures.
关键词： plasmonic nanoparticles,heterogeneous catalysis,photo-electrocatalysis,oxygen evolution reaction (OER),hydrogen evolution reaction (HER)
更新于2025-09-09 09:28:46
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Pyrite-Type CoS2 Nanoparticles Supported on Nitrogen-Doped Graphene for Enhanced Water Splitting
摘要： It is extremely meaningful to develop cheap, highly efficient, and stable bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER) to promote large-scale application of water splitting technology. Herein, we reported the preparation of CoS2 nanoparticles supported on nitrogen-doped graphene (CoS2@N-GN) by one-step hydrothermal method and the enhanced electrochemical efficacy for catalyzing hydrogen and oxygen in water electrolysis. The CoS2@N-GN composites are composed of nitrogen-doped graphene and CoS2 nanocrystals with the average size of 73.5 nm. Benefitting from the improved electronic transfer and synergistic effect, the as-prepared CoS2@N-GN exhibits remarkable OER and HER performance in 1.0 M KOH, with overpotentials of 243 mV for OER and 204 mV for HER at 10 mA cm?2, and the corresponding Tafel slopes of 51.8 and 108 mV dec?1, respectively. Otherwise, the CoS2@N-GN hybrid also presents superior long-term catalytic durability. Moreover, an alkaline water splitting device assembled by CoS2@N-GN as both anode and cathode can achieve a low cell voltage of 1.53 V at 60 ?C with a high faraday efficiency of 100% for overall water splitting. The tremendously enhanced electrochemical behaviors arise from favorable factors including small sized, homogenously dispersed novel CoS2 nanocrystals and coupling interaction with the underlying conductive nitrogen-doped graphene, which would provide insight into the rational design of transition metal chalcogenides for highly efficient and durable hydrogen and oxygen-involved electrocatalysis.
关键词： water splitting,HER/OER,graphene,nanoparticle,composite,cobalt sulfide
更新于2025-09-09 09:28:46
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Microwave-Assisted Solvothermal One-Pot Synthesis of RuO <sub/>2</sub> Nanoparticles: First Insights of Its Activity Towards Oxygen and Chlorine Evolution Reactions
摘要： A microwave-assisted solvothermal method is proposed as a rapid and low-cost fabrication procedure of RuO2 nanoparticles using citric acid as stabilizing agent in ethylene glycol, and H2O2 as oxidizing agent at 180 °C. Structural and morphological characterizations of the powder are investigated using X-Ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis shows that there is a synergic effect to obtain RuO2 nanoparticles when 6% v/v H2O2 is added followed by a calcination of the powder, due to reactive oxygen intermediates (1O2, HO(cid:0) 2, 2, HO* *OH) generated in the first stage. TEM and SEM images of as-synthesized material exhibit an uniform particle distribution (PSD) of RuO2 nanoparticles with averaged diameter of ca. 38 nm, and its indexing indicates the RuO2 stoichiometry with high degree of crystallinity. The preliminary electrocatalytic performance of RuO2 nanoparticles coated on Ti is investigated using voltammetry and electrochemical impedance spectroscopy (EIS), towards the oxygen (OER) and chlorine evolution reaction (CER) in 1 mol L(cid:0) 1 H2SO4 and 0.1 mol L(cid:0) 1 NaCl, respectively. Cyclic voltammograms of RuO2 display typical behaviors for OER and CER at 1.25 and 1.1 V vs Ag/AgCl, respectively. A Tafel slope of 44 mV dec(cid:0) 1 corrected for ohmic drop was obtained in sulfate media which confirmed the OER mechanism in the absence of chlorides; while this parameter is around 25 mV dec(cid:0) 1 in NaCl (CER), strongly depending on the chloride concentration and the extent of OER input. In NaCl media, the energy barriers represented by the charge transfer resistances for CER are overcome at more positive potentials than for OER, and a greater activity of the O2 evolution is observed as the potential became more positive.
关键词： Microwave,CER,OER,Electrocatalysis,Solvothermal,RuO2 Nanoparticles
更新于2025-09-09 09:28:46