Electrochemical N-N Oxidatively Coupled Dehydrogenation of 3,5-Diamino-1-1,2,4-triazole for Value-Added Chemicals and Bipolar Hydrogen Production.

Electrochemical H production from water favors low-voltage molecular oxidation to replace the oxygen evolution reaction as an energy-saving and value-added approach. However, there exists a mismatch between the high demand for H and slow anodic reactions, restricting practical applications of such hybrid systems. Here, we propose a bipolar H production approach, with anodic H generation from the N-N oxidatively coupled dehydrogenation (OCD) of 3,5-diamino-1-1,2,4-triazole (DAT), in addition to the cathodic H generation. The system requires relatively low oxidation potentials of 0.872 and 1.108 V vs RHE to reach 10 and 500 mA cm, respectively. The bipolar H production in an H-type electrolyzer requires only 0.946 and 1.129 V to deliver 10 and 100 mA cm, respectively, with the electricity consumption (1.3 kWh per m H) reduced by 68%, compared with conventional water splitting. Moreover, the process is highly appealing due to the absence of traditional hazardous synthetic conditions of azo compounds at the anode and crossover/mixing of H/O in the electrolyzer. A flow-type electrolyzer operates stably at 500 mA cm for 300 h. Mechanistic studies reveal that the Pt single atom and nanoparticle (Pt) optimize the adsorption of the S active sites for H production over the Pt@VS cathodic catalysts. At the anode, the stepwise dehydrogenation of -NH in DAT and then oxidative coupling of -N-N- predominantly form azo compounds while generating H. The present report paves a new way for atom-economical bipolar H production from N-N oxidative coupling of aminotriazole and green electrosynthesis of value-added azo chemicals.