Tuning Coal into Graphene-Like Nanocarbon for Electrochemical H2O2 Production with Nearly 100% Faraday Efficiency

Abstract

Electrochemical reduction of O2 to produce H2O2 provides the most promising alternative to the current anthraquinone process, whereas an electrocatalyst that is cost-effective and has rich resources, excellent oxygen reduction reaction (ORR) activity, and dominant two-electron (2e–) selectivity is highly required. Herein, by using inexpensive and earth-abundant anthracite coal as the precursor along with the KOH activation method, a defective graphene-like carbon (DGLC) nanomaterial has been successfully constructed. The as-prepared DGLC material features a graphene-like morphology, a hierarchical porous structure, a high surface area, abundant defects/edges, and a high content of ether functional groups, which endow it with excellent ORR activity, dominant 2e– selectivity, and high stability toward H2O2 synthesis in alkaline media. Remarkably, when employed as the electrocatalyst in H-cell, it can achieve a high H2O2 production rate of 355.0 mmol L–1 h–1 cm–2 gcat–1 with nearly 100% Faraday efficiency, which is superior to most carbon-based ORR catalysts. Experimental and theoretical studies describe that such high ORR activity and selectivity of DGLC are highly associated with its defect degree and ether groups (C–O–C) content, respectively, which contribute together to boost the superior 2e– ORR performance. This finding will be very helpful for designing a carbon-based 2e– ORR electrocatalyst toward H2O2 synthesis.