Vinegar-derived nitrogen-based multi-heteroatom doped bifunctional All-carbon electrodes for overall water splitting in a wide pH range

Abstract

All-carbon electrodes are promising green bifunctional catalytic electrodes for cost-effective water splitting technology. Herein, we report on a series of N-based multi-heteroatom doped carbon quantum dots (CQDs) with varied concentrations that are placed on vertical graphene (VG) as bifunctional vinegar-derived all-carbon electrodes for total water splitting. A systematic analysis of the electrocatalytic performance of catalytic electrodes shows that N,S-VG-CQDs-0.8 exhibited enhanced hydrogen evolution reaction (overpotentials of 94 ± 10 mV and 97 ± 10 mV in acid and alkaline electrolytes, respectively) and oxygen evolution reaction (overpotentials of 305 ± 10 mV and 327 ± 10 mV in acid and alkaline electrolytes, respectively) performances. The unique strong synergistic impact of pyridine N and thiophene S, the increased concentration of CQDs, and the high electronegativity of the N and S atoms are all responsible for the improvement of N, S co-doped electrode performance, according to experimental findings and DFT calculations. In addition, the catalytic electrodes exhibit hydrogen evolution reaction (HER) stability (10 h) and Faraday efficiency (89.5 ± 2 %) in a wide pH range. This study provides significant information on the advancement and commercialization of high-performance all-carbon electrodes for water-splitting technology-based green hydrogen production.