Electrochemically Modulated Multi-Metal Sulfides/3D-Graphene Scaffold for Sustainable Energy Generation and Storage
Authors: Sasidharan Sankar , Sanchez Jaime Sanchez , Mirehbar Keyvan , Sasikala Devi Assa Aravindh , Xia Zhenyuan 
Published: February 2024

Transition metal-based compounds (TMCs), especially sulfides and phosphides represent a class of promising non-precious metal oxygen electrocatalysts (OER and ORR) due to their advantages of abundance, low cost, and environmental friendliness. The effective modulation of electronic structure from synergistic interactions between the constituents and the favourable adsorption of crucial intermediates during electrochemical reactions is possible while using multi-metal transition metal-based sulfides and phosphides. Moreover, recent studies report that TMCs with heteroatom-doped carbonaceous materials display excellent bifunctional ORR/OER properties in alkaline environment, benefitting from the fast interfacial electron transfer and the synergistic effects originating from the chemical coupling between metallic atoms and carbon materials. In this regard, Graphene could effectively enhance the electrical properties and limit the volume expansion of the TMCs, improving the durability of the catalyst. However, there are several challenges associated processing of these catalysts or catalyst systems in a scalable route. Designing these scalable electrodes as porous structures is critical for their effective utilization in energy systems. Electrodeposition is an ideal and sustainable strategy that eliminates the calcination step in electrode processing and saves time. In the case of metal sulfides, adopting electrodeposition over 3D foams like of graphene will help to eliminatesimultaneous steps and reduce the toxic gas evolution during heating of precursors. The electrochemical processing will also help to achieve structural designs capable of delivering higher catalytic sites and a controlled ratio of metal elements, enabling excellent catalytic performance for the composition. More importantly, a sturdy interaction between the substrates and the deposited coatings, forming composite structures gives the electrocatalysts exceptional durability.

Herein, we report an electrodeposition process of ternary, quaternary, and quinary transition metal-based sulfide electrocatalysts for OER and ORR in alkaline media. We will be discussing the versatile deposition process for multi-metal sulfides over 3D porous graphene foams materialized by chemical vapour deposition. The detailed electrochemical characterization of the catalyst compositions will be supported by first principle-based investigations on oxygen electrochemistry over modelled catalyst surfaces. Finally, the the practical application of rechargeable structural batteries using these transition metal-based catalysts will be demonstrated along with the performance factors.

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