Synthesis Of Iron-based Metalloid Interstitial Compounds And Electrocatalytic Water Splitting And Organics Conversion

The use of renewable,intermittent solar energy,wind energy,tidal energy,etc.,is converted into low-voltage electric drive to split water to obtain green secondary energy hydrogen energy with high energy utilization efficiency and no pollutants when used.However,with the existing technical conditions,high-cost commercial catalysts containing a large amount of precious metals are usually used in industrial electrocatalytic water splitting for hydrogen production.At the same time,the high-energy-consumption oxygen evolution reaction at the other pole accompanied by the hydrogen evolution reaction restricts the large-scale application of water electrolysis for hydrogen production.Therefore,it is of great application significance to rationally design the hydrogen evolution catalyst and find a more practical and high value-added chemical reaction to replace the anode oxygen evolution reaction.In addition,choosing some industrially important reduction or hydrogenation reactions to replace the cathodic hydrogen evolution reaction is expected to further reduce the energy consumption of the reaction and increase the economic benefits of electrochemical production.We noticed that iron(Fe)-based materials are inexpensive,easy to synthesize,and Fe-P,Fe-S and other structures formed by Fe and non-metals exist in various oxidoreductases in nature and are considered as active centers.Therefore,it is of great significance to construct an ideal electrocatalytic organic selective oxidation or reduction catalyst based on the above principles.In this paper,based on Fe-based metal(like)interstitial compounds,we designed a catalyst for electrocatalysis through optimization and regulation of electronic structure.Catalytic water splitting and electrocatalytic organic selective conversion materials,and study their catalytic activity mechanism in detail.The main research contents are as follows:1.We designed and fabricated a novel porous structured carbon-coated Mo O₂-FeP heterojunction nanospindle(Mo O₂-FeP@C)composition by interface engineering.Mo O₂-FeP@C exhibited excellent HER and EOR activities.Through XPS and DFT calculations,it was found that FeP was the main HER active component,and Mo O₂was the main EOR active component.When 5-hydroxymethylfurfural(5-HMF)was chosen as the model reaction for EOR,the conversion of 5-HMF was close to 100%and the yield of selective synthesis of 2,5-furandicarboxylic acid(2,5-FDCA)was 98.6%.The electrolyzer using Mo O₂-FeP@C for cathodic production of H₂and anodic synthesis of high additional FDCA requires only a voltage of 1.486 V to obtain a current of 10 m A cm^-2,and can be driven by a solar cell system with an output voltage of 1.45 V,indicating that the potential of catalysts to convert intermittent energy sources such as solar energy.2.It is meaningful to produce value-added chemicals by paired electro-reduction and electro-oxidation of organics with water as raw material.A comprehensive understanding of the reaction mechanism is crucial for catalyst design and development in related fields.Choosing a suitable pairing reaction system can help improve the overall energy utilization efficiency and create more economic value.To this end,we designed and synthesized a self-supporting Fe-Mo-based phosphide heterojunction and systematically studied the electroreduction and electrooxidation mechanisms of organic compounds on it.The results show that the active H*species for organic electroreduction are derived from water.As for organic electro-oxidation,among various oxygens(OH*,OOH*,and O*),the OH*radical originating from the first step of water dissociation was identified as the active species,and since H*and OH*were derived from the water,and therefore in this system.Furthermore,a clear reaction pathway and its pairing advantages are proposed based on theoretical calculations.The paired electrolyzer powered by a solar cell exhibits a low voltage of 1.594 V at 100 m A cm^-2,a Faradaic efficiency of?99%,and excellent cycling stability.This work provides guidance for sustainable synthesis of various value-added chemicals via paired electrocatalysis.3.The Fe-S structure is widely involved in various catalytic oxidation and reduction reactions in organisms in nature.Therefore,Fe-containing sulfides have been used for reference in the development and application of industrial catalysts due to their large number of bonding structures.Therefore,Fe sulfides are also considered to be binary bimetallic sulfides with nanopolyhedral structures(Fe S₂-Co S₂NPs)by controllable sulfurization of Prussian blue-like precursors(Co₂[Fe(CN)₆])with nanostructures.,the nano-polyhedron has an ideal specific surface area,and also exhibits ideal HER and EOR activities.In addition,the Fe S₂-Co S₂NPs material exhibits high activity in the electrocatalytic reduction of nitroaromatic compounds and is suitable for different driving potentials.The high selectivity of different reduction products(oxygenated azo compounds,azo compounds and amino compounds),and the Fe S₂-Co S₂NPs material reaction can also efficiently catalyze the organic oxidation of glucose(Glu).The ideal performance can be contributed to the S vacancies during the formation of the sulfide as well as the interaction between Co and Fe in the FeS₂-CoS₂NPs material.