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

Electrochemical H2 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 H2 and slow anodic reactions, restricting practical applications of such hybrid systems. Here, we propose a bipolar H2 production approach, with anodic H2 generation from the N–N oxidatively coupled dehydrogenation (OCD) of 3,5-diamino-1H-1,2,4-triazole (DAT), in addition to the cathodic H2 generation. The system requires relatively low oxidation potentials of 0.872 and 1.108 V vs RHE to reach 10 and 500 mA cm–2, respectively. The bipolar H2 production in an H-type electrolyzer requires only 0.946 and 1.129 V to deliver 10 and 100 mA cm–2, respectively, with the electricity consumption (1.3 kWh per m3 H2) 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 H2/O2 in the electrolyzer. A flow-type electrolyzer operates stably at 500 mA cm–2 for 300 h. Mechanistic studies reveal that the Pt single atom and nanoparticle (Pt1,n) optimize the adsorption of the S active sites for H2 production over the Pt1,n@VS2 cathodic catalysts. At the anode, the stepwise dehydrogenation of −NH2 in DAT and then oxidative coupling of −N–N– predominantly form azo compounds while generating H2. The present report paves a new way for atom-economical bipolar H2 production from N–N oxidative coupling of aminotriazole and green electrosynthesis of value-added azo chemicals.