Tailoring trimetallic CoNiFe oxide nanostructured catalysts for the efficient electrochemical conversion of methane to methanol

Abstract

The electrochemical conversion of methane to methanol and other oxygenates is of considerable importance to address pressing environmental and energy issues. However, achieving high productivity and selectivity when converting methane under mild conditions remains a significant challenge. Here we report on a new approach for simultaneously promoting the electrochemical oxidation of methane and the electrochemical reduction of nitrogen over novel CoNiFe trimetallic oxides by tailoring their morphology, composition, and electronic structure. The optimized Co_0.6Ni_0.4Fe₂O₄–N/C nanocubes (NCs) exhibited high performance for the direct methane conversion (DMC) to oxygenates with a low potential (0.54 V vs. Ag/AgCl) and a splendid overall yield and faradaic efficiency (FE) of ∼2323.5 mmol g_cat.⁻¹ h⁻¹ (methanol: 1925.4; 2-propanol: 398.1) and 14.62% (methanol: 9.03%; 2-propanol: 5.59%), respectively. An integrated electrochemical system with Co_0.8Ni_0.2Fe₂O₄–N/C as the cathode and Co_0.6Ni_0.4Fe₂O₄–N/C as the anode has been assembled and tested, showing remarkable performance for the simultaneous nitrogen reduction in the cathodic compartment and the DMC in the anodic compartment. This work provides new inspiration for the development of next-generation electrocatalysts for the conversion of methane into value-added chemicals and fuels.