| Due to the increasingly severe environmental issues and energy crisis,it has become imperative to develop renewable and clean sources of energy as a replacement for conventional fossil fuels.Electrocatalysis provides an ideal technical solution to current environmental and energy problems by enabling hydrogen production through water splitting and carbon dioxide conversion into various organic low-carbon fuels,thereby helping mitigate greenhouse gas concentrations in the atmosphere.Although noble metals display remarkable catalytic activity for electrocatalysis,their exorbitant costs restrict their practical applications.Consequently,exploring non-noble alternatives that offer better performance at a lower expense is crucial to advancing sustainable clean energy technologies.Recently,transition metals and bio-carbon materials have garnered increasing attention due to their abundant reserves and low cost.However,their catalytic performance remains limited by insufficient active sites,poor stability,and other shortcomings,resulting in a significant gap compared to precious metals.Fe can serve as an effective dopant for regulating the electrochemical behavior of transition metal materials owing to its unique electronic geometry and multiple valence distribution.However,the mechanism of Fe doping remains inadequately explored.Therefore,this study investigates the electrocatalytic performance of Zn-based and biocarbon-based materials in water splitting and CO2 reduction(CO2RR)through Fe doping or modification.Analytical characterization and electrochemical tests confirm that Fe can effectively regulate the catalytic activity of these materials.The specific research is as follows:(1)A simple impregnation and heat treatment process was used to incorporate Fe and biocarbon(BC)into lamellar porous composites,denoted as Fe@BC,for electrocatalytic water splitting.It has been observed that Fe is distributed on the surface of BC carrier in the form of oxides.The introduction of Fe leads to a transformation in the crystal phase and morphology of BC,resulting in a porous layered structure.This process also generates Fe-O bonds and numerous oxygen vacancies on its surface,which effectively modulate the electronic structure of the catalyst and reduce charge transfer resistance.This facilitates rapid electron and charge transfer to the active site of the catalyst for electrocatalytic oxygen evolution(OER)and hydrogen evolution(HER)reactions.The incorporation of Fe sites significantly improved the electrochemical performance of Fe@BC.The composite catalyst achieved optimal performance with a Fe loading of 1.42%,delivering 20 mA cm-2 at potentials as low as-0.28 V vs.RHE for HER and 1.50 V vs.RHE for OER,while maintaining stable activity under the current density(10.0 mA cm-2)in 1.0 mol L-1 KOH for over 48 h.Moreover,this bifunctional electrode enables a high-performance alkaline water electrolyzer with 10.0 mA cm-2 at a cell voltage of 1.69 V,which is higher than that reported for most non-precious metal catalysts(2)The bimetallic FeZn compound catalyst with a three-dimensional nanosheet array structure was synthesized through hydrothermal control of Fe doping,and its electrocatalytic performance for CO2RR was investigated.It has been observed that alterations in the molar ratio of Fe and Zn lead to changes in the surface atomic structure.With an increase in Fe content,there is a greater concentration of charges on the surface of Fe,while electrons are concentrated on the surfaces of Zn and O,thereby facilitating proton transfer from Zn to Fe and promoting intermediate protonation during CO2RR.The Fe3Zn-LDHs exhibited superior electrochemical performance in CO2RR,with a low overpotential of only-0.47 V vs.RHE and a Tafel slope of 233.6 mV·dec-1 at the current density of 10.0 mA·cm-2.At-0.40V vs.RHE,the CO Faraday efficiency reached an impressive value of 86.0%,surpassing that of most reported transition metal-based electrocatalysts. |
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