Regulating Reconstruction‐Engineered Active Sites for Accelerated Electrocatalytic Conversion of Urea

Abstract

AbstractReconstruction‐engineered electrocatalysts with enriched high active Ni species for urea oxidation reaction (UOR) have recently become promising candidates for energy conversion. However, to inhibit the over‐oxidation of urea brought by the high valence state of Ni, tremendous efforts are devoted to obtaining low‐value products of nitrogen gas to avoid toxic nitrite formation, undesirably causing inefficient utilization of the nitrogen cycle. Herein, we proposed a mediation engineering strategy to significantly boost high‐value nitrite formation to help close a loop for the employment of a nitrogen economy. Specifically, platinum‐loaded nickel phosphides (Pt‐Ni2P) catalysts exhibit a promising nitrite production rate (0.82 mol kWh−1 cm−2), high stability over 66 h of Zn‐urea‐air battery operation, and 135 h of co‐production of nitrite and hydrogen under 200 mA cm−2 in a zero‐gap membrane electrode assembly (MEA) system. The in situ spectroscopic characterizations and computational calculations demonstrated that the urea oxidation kinetics is facilitated by enriched dynamic Ni3+ active sites, thus augmenting the “cyanate” UOR pathway. The C−N cleavage was further verified as the rate‐determining step for nitrite generation.