Facilitating Anodic Ammonia Oxidation over Trace Cobalt-Substituted Solid Solution of Platinum to Boost Direct Ammonia Fuel Cell up to 853.75 mW cm–2

Abstract

Low-temperature direct ammonia fuel cell (DAFC) is a key technology for decarbonized electric generation on a large scale and with high safety. However, as the core of DAFC, the anodic ammonia oxidation reaction (AOR) still suffers from unsatisfactory activity and an ambiguous reaction mechanism. Herein, inspired by homogeneously catalyzed oxidation of ammonia, a nucleophilic attack mechanism that loosens the steric and charge constraints in heterogeneous catalysis is theoretically predicted and experimentally verified by a three-stage isotope-labeling experiment. Guided by this more practical mechanism, a highly efficient AOR process is realized over trace cobalt-substituted solid solution of platinum, delivering a superior current density of 83.96 A g^–1 at 5 mV s^–1. The assembled DAFC exhibits a remarkable power density of up to 853.75 mW cm^–2 at 60 °C and can operate steadily for 300 h with a performance retention rate of 95.14%, propelling the application of low-temperature DAFC to a more practical era.