Nanoporous Boron-Doped Diamond-Like Carbon (DLC) Electrode for Electrocatalytic Nitrate Reduction

Abstract

The electrocatalytic nitrate reduction reaction (NO3RR) is regarded as a promising strategy to rebalance the global nitrogen cycle. However, the multi-step electron and proton transfer involved in NO3RR severely compromises NO3RR's Faradaic efficiency; thus, efficient electrocatalysts for NO3RR are desired to accelerate this process. Herein, we applied the "laser direct-writing" method to fabricate a nanoporous boron-doped DLC electrode for efficient electrocatalytic NO3RR, and the catalytic activity was optimized by modulating the boron doping concentration in the DLC catalyst. It is noted that the electrode achieved a high Faradaic efficiency of 80% and an ammonia yield rate of 550 μg cm⁻² h⁻¹ at a potential of -0.59 V vs. RHE. In situ Raman spectroscopy combined with X-ray photoelectron spectroscopy (XPS) and multiple characterization techniques indicated that B0.57DG effectively promoted the reduction of intermediate species. Strong reducing H* species can accelerate the hydrogenation process in nitrate electroreduction, thereby enhancing the efficiency of ammonia synthesis.