Progress on Entropy Production Engineering for Electrochemical Catalysis
As for the accurate synthesis of high-performance electrochemical catalysts with good robustness,the rational design on atomic level is still a priority.Entropy,as one of the most significant thermodynamic parameters,measure the disorder of a system,which is a significant quantity for materials.The values are primarily determined by the crystal structure,magnetic moments and the atomic and electronic vibrations of the materials.According to the configurational entropy of the system,we usually divide the material into low entropy materials(LEMs)(∆Smix<1R),medium entropy materials(MEMs)(1R≤∆Smix≥1.5R)and high entropy materials(HEMs)(∆Smix>1.5R),where R is the gas molar constant.HEMs are those that consist of five or more major elements of roughly equal proportion,in a highly uniform,random manner,which typically consist of one or two major elements compared to traditional materials.As the entropy value increases,the intrinsic physical,chemical and structural properties of the material change accordingly,resulting in special physicochemical properties(e.g.,strength,electrical conductivity,corrosion resistance,etc.).Moreover,due to its multi-element combination,the HEMs can be precisely regulated by selecting different elements and their ratios according to the needs,which overcomes the limitations of the traditional catalysts in terms of relatively single component,structure and field of application.Importantly,the synergistic high entropy effect and multi-component arrangement at the atomic-level interface produced by the coexistence of different metal elements in HEMs can exert higher catalytic activity,selectivity and stability in different reactions.This has attracted a lot of attention from researchers,especially in the field of electrocatalysis.In this review systematically summarizes the fundamental concepts of high-entropy catalysts(HECs),synthetic approaches("top-down"and"bottom-up"),and the structure-performance relationships of HEMs in different types of electrocatalytic processes,mainly including hydrogen evolution reaction(HER),oxygen evolution reaction(OER),oxygen reduction reaction(ORR),alcohol oxidation reaction(AOR),nitrogen reduction reaction(NRR),and carbon dioxide reduction reaction(CO2RR)etc.Thus,the advantages and potential of high-performance electrocatalysts based on entropy increase engineering are illuminate.At the same time,it is summarized and discussed that HECs are currently facing problems and challenges such as complicated material rational design,complex preparation process,the mechanism of electrocatalytic processes in which multiple metal elements interact is ambiguous,and poor stability under extreme reaction conditions.Finally,the main problems and challenges facing the current HECs research.We look forward to the future design ideas,synthesis methods different research areas and industrial applications of HECs based on entropy enhancement engineering.
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