Earth‐Abundant Amorphous Electrocatalysts for Electrochemical Hydrogen Production: A Review

Abstract

Electrochemical water splitting provides a promising approach to store renewable electricity in the form of hydrogen on a grand scale. However, the current techniques for large‐scale electrochemical hydrogen production rely on the use of expensive and scarce noble‐metal catalysts making it uncompetitive to traditional methods using fossil fuels. Thus, replacing noble‐metal electrocatalysts with cheap materials made of abundant elements holds the key to achieve the cost‐effectiveness. Recently, amorphous electrocatalysts emerged as promising candidates due to their unique physical and chemical properties compared with their crystalline counterparts leading to superior catalytic performance. Given the rapid advances made in the design, synthesis, and development of amorphous catalysts, namely monometallic and multimetallic borides, sulfides, phosphides, oxides, and hydroxides based on transition metals, the recent progress on compositional designs, microstructure, morphology, electronic properties, and interaction with host materials are reviewed critically. Special attention is paid to uncover the main strategies adopted in each material category and the underlying structure–property relationship that lead to improved hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. As a result, guidance for the design and synthesis of novel amorphous electrocatalysts with high performance for large‐scale electrochemical water splitting application is provided.

Recent advances in amorphous electrocatalysts for oxygen evolution reaction

“…In addition, abundant defects in amorphous materials can improve the diffusion property that facilitates the transportation of reactants and products ( Zhai et al, 2021 ). Moreover, amorphous materials have higher structural flexibility through facile morphology engineering ( Zhang D et al, 2021 ).…”

Progress and Perspectives in Photo‐ and Electrochemical‐Oxidation of Biomass for Sustainable Chemicals and Hydrogen Production

“…Its working principles and some of the most recent scientific developments are reviewed in detail in other dedicated reviews. [41,[46][47][48][49] In all cases OER involves multi-proton-coupled electron-transfer steps, suffering from the limitation of suboptimal scaling relation between OOH and OH adsorption energies, which is the major bottleneck and requires a cell potential above 1.23 V. [7] In biomass electrolysis, a complete oxidation process, also known as electrochemical reforming, such as methanol electrolysis, produces CO 2 under acidic condition (CO 3 2− under alkaline) in the anode and H 2 at the cathode, resulting in a maximum proton utilization. The partial oxidation of certain feedstocks could concomitantly generate H 2 and value-added chemicals.…”

Facile Substrate-Agnostic Preparation of High-Performance Regenerative Water Splitting (Photo)electrodes

“…Currently, progress has been made in utilizing cheaper earth-abundant metals in both substrates and electrocatalysts, with Ni-based multimetallic catalysts exhibiting considerable performance in both OER and HER reactions . Our attention here is particularly toward NiFe layered double hydroxides (LDH), whereby a considerable number of studies have reported its use as an effective OER electrocatalyst. − NiFe LDH has been reportedly synthesized by using solvothermal, coprecipitation, and electrodeposition methods and demonstrated satisfactory performances of around 260–350 mV overpotential at 10 mA/cm 2 with reported OER operational stability of 10 h and beyond.…”