Influence of active hydrogen on pathway selection in electrochemical nitrate reduction
Junchao Yu, Zichao Xi, Jinhui Su, Peng Jing, Xuan Xu, Baocang Liu, Yu Wang, Jun Zhang
Abstract
Electrochemical nitrate reduction reaction in alkaline condition involves two reactants, the nitrate ( NO 3 − ) and the water (H 2 O). Although the significance of the active ∗H species produced from the dissociation of H 2 O has been proved, the correlation between the reaction pathways and the ∗H species is often overlooked. Herein, Co(OH) 2 –CoP supported Ru nanoclusters is designed for electrocatalytic nitrate reduction and shows a record-high faradaic efficiency of 99.7% at an ultralow potential of 0.1 V versus reversible hydrogen electrode. Experiments and theoretical calculations reveal that in addition to the faster proton transfer kinetics, the reaction pathway is strongly correlated with ∗H supply with the aid of CoP, that is, the direct hydrogenation of ∗NOH instead of deprotonation over Ru sites with the lowest energy barrier is promoted with the moderate production of ∗H species. This work provides new insights into the impact of ∗H species on the thermodynamics and kinetics of electrocatalytic nitrate reduction. • Ru/Co(OH) 2 –CoP shows a faradaic efficiency of 99.7 % for NH 3 at 0.1 V vs. RHE in electrocatalytic nitrate reduction. • The nitrate reduction reaction pathway is strongly correlated with ∗H supply. • The direct hydrogenation of ∗NOH is promoted with the moderate production of ∗H species.