Abstract

An increasing emphasis on energy storage has resulted in a surge of R&D efforts into producing catalyst materials for the hydrogen evolution reaction (HER) with emphasis on decreasing the usage of platinum group metals (PGMs). Alkaline water electrolysis holds promise for satisfying future energy storage demands, however the intrinsic potential of this technology is impeded by sluggish reaction kinetics. Here, we summarize the latest efforts within alkaline HER electrocatalyst design, where these efforts are divided between three catalyst design strategies inspired by the three prevailing theories describing the pH-dependence of the HER activity. Modifying the electronic structure of a host through codoping and creating specific sites for hydrogen/hydroxide adsorption stand out as promising strategies. However, with the vast amount of possible combinations, emphasis on screening parameters is important. The authors predict that creating a codoped catalyst using the first strategy by screening materials based on their hydrogen, hydroxide and water binding energies, and utilizing the second and third strategies as optimization parameters might yield both active and stable HER catalyst materials. This strategy has the potential to greatly advance the current status of alkaline water electrolysis as an energy storage option.

Highlights

  • The hydrogen evolution reaction is an important electrochemical process with its critical roles in water electrolyzers, the chlor-alkali industry and in chlorate cells [1,2], and while it has been studied for over a century, many of its intrinsic qualities remain elusive.This review will explore the realm of catalyst design pertaining to the alkaline hydrogen evolution reaction

  • Similar to the results reported by Gao et al [74], the heteroatomdoped carbon aided in protecting the nanorods from dissolution, resulting in a fairly stable catalyst material as determined by inductively coupled plasma mass spectrometry results where the content of nickel leached was low

  • This review detailed the development of catalyst materials for the hydrogen evolution reaction in alkaline electrolytes

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Summary

Introduction

The hydrogen evolution reaction is an important electrochemical process with its critical roles in water electrolyzers, the chlor-alkali industry and in chlorate cells [1,2], and while it has been studied for over a century, many of its intrinsic qualities remain elusive. There are many methods available to create novel catalyst materials, such as “Modifying the Electronic Structure” (elemental doping, alloying), “Creating Specific Sites for Hydroxide and Hydrogen Adsorption” (phase regulation and hybridising 2D substrates) and “Altering the Surface of a Catalyst” (defect, facet, and interface engineering and use of coatings) [3,14]. These three strategies may be realized by following the more specific routes parenthesized, none of these methods are one-way tickets to achieving the unparenthesized goal. While the three ensuing sections “Modifying the Electronic Structure”, “Creating Specific Sites for Hydroxide and Hydrogen Adsorption”, and “Altering the Surface of a Catalyst” refer to specific aspects of HER catalysis, the resulting performance of the catalyst will to some degree be a function of changes involving all three aspects

Modifying the Electronic Structure
Phosphides
Nitrides
Co-Doping
Chalcogenides
Sulfides
Selenides
Tellurides
Dichalcogenides
Creating Specific Sites for Hydroxide and Hydrogen Adsorption
Altering the Surface of a Catalyst
Strain
Additional Geometrical Modification Methods
Perspective
Findings
Conclusions
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