N-doped vertical graphene arrays/carbon quantum dots derived from vinegar residue as efficient water-splitting catalyst in a wide pH range

In order to develop water splitting as a sustainable technology, cost-effective and green electrocatalysts are urgently needed. We report a fabrication of an efficient self-supported whole-carbon electrocatalyst for overall water splitting in a wide pH range, which consist of nitrogen-doped vertically aligned graphene arrays and nitrogen-doped carbon quantum dots (N-VG-CQDs) prepared from vinegar residue. N-VG-CQDs electrocatalyst displays excellent electrocatalytic performances towards hydrogen evolution reaction (overpotentials of 218 and 238 mV in 1.0 M KOH and 0.5 M H2SO4, respectively), as well as outstanding performances towards oxygen evolution reaction (overpotentials of 383 and 497 mV in 1.0 M KOH and 0.5 M H2SO4, respectively). In addition, N-VG-CQDs acts as a self-supporting bifunctional electrocatalyst, exhibiting good stabilities in both acidic and alkaline electrolytes and an excellent Faraday efficiency (about 83 %). This study sheds light on the usage of vinegar residue towards the development of cost-effective whole-carbon electrocatalysts in water splitting. And the study also facilitates the use of environmental pollutions to prepare electrocatalysts for water splitting and advances the development of the water splitting industry.