Electrochemical N–N Oxidatively Coupled Dehydrogenation of 3,5-Diamino-1<i>H</i>-1,2,4-triazole for Value-Added Chemicals and Bipolar Hydrogen Production
Jiachen Li, Yang Li, Yuqiang Ma, Zihang Zhao, Huarong Peng, Tao Zhou, M. Xu, Daidi Fan, Haixia Ma, Jieshan Qiu, Zhengxiao Guo
Abstract
High Resolution Image Download MS PowerPoint Slide Electrochemical H 2 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 2 and slow anodic reactions, restricting practical applications of such hybrid systems. Here, we propose a bipolar H 2 production approach, with anodic H 2 generation from the N–N oxidatively coupled dehydrogenation (OCD) of 3,5-diamino-1 H -1,2,4-triazole (DAT), in addition to the cathodic H 2 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 H 2 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 m 3 H 2 ) 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 2 /O 2 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 (Pt 1,n ) optimize the adsorption of the S active sites for H 2 production over the Pt 1,n @VS 2 cathodic catalysts. At the anode, the stepwise dehydrogenation of −NH 2 in DAT and then oxidative coupling of −N–N– predominantly form azo compounds while generating H 2 . The present report paves a new way for atom-economical bipolar H 2 production from N–N oxidative coupling of aminotriazole and green electrosynthesis of value-added azo chemicals.