Robust copper nanocrystal/nitrogen-doped carbon monoliths as carbon monoxide-resistant electrodes for methanol oxidation reaction

Abstract

Noble metal-based electrocatalysts present high activities for methanol oxidation reaction (MOR), but are limited by their high cost, low stability and poor resistance to carbon monoxide (CO) poisoning. The development of active and stable non-noble metal electrocatalysts for MOR is desired, but remains a challenge. Herein, we report a simple strategy to make copper nanocrystal/nitrogen-doped carbon (Cu/N-C) monoliths, which can serve as active and robust electrodes for MOR. Copper nanocrystals were electrochemically deposited onto a conductive polyaniline hydrogel and calcined to form Cu/N-C monolith, where the active copper nanocrystals are protected by nitrogen-doped carbon. Owing to their extremely high electrical conductivity (1.25 × 105 S cm−1) and mechanical robustness, these Cu/N-C monoliths can be directly used as electrodes for MOR, without using substrates or additives. The optimal Cu/N-C (FT) @500 monolith shows a high MOR activity of 189 mA cm−2 at 0.6 V vs. SCE in alkaline methanol solution, superior to most of reported Cu-based MOR catalysts. Cu/N-C (FT)@500 also presents a better stability than Pt/C catalyst in the long-term MOR test at high current densities. Upon carbon monoxide (CO) poisoning, Cu/N-C (FT)@500 retains 96% of its MOR activity, far exceeding the performance of Pt/C catalyst (61% retention). Owing to its facile synthesis, outstanding activity, high stability and mechanical robustness, Cu/N-C (FT)@500 monolith is promising as a low-cost, efficient and CO-resistant electrocatalyst for MOR.