Graphene oxide/cobalt-based nanohybrid electrodes for robust hydrogen generation

Abstract Low-cost nanostructured hybrid materials and the optimization of their structural design present an opportunity to achieve high performance and stable renewable energy devices. Here we used electrospinning to homogeneously embed graphene oxide (GO) nanosheets within the one-dimensional structure of cobalt-based nanohybrids (CoNHs). In particular, we focus on the performance of these nanohybrids in Na 2 S/Na 2 SO 3 aqueous electrolyte (pH = 13) due to its wide application in photocatalytic and photoelectrochemical (PEC) devices. We demonstrate that the addition of GO can remarkably reduce the charge transfer resistance from 4.4 Ω to 2.5 Ω for the 0 wt% GO/CoNHs and the 12 wt% GO/CoNHs, respectively. Furthermore, the CoNHs display outstanding electrochemical long-term stability, as the overpotential required to keep J  = −10 mA cm −2 is invariable for over 42 h. The structural characterization of the nanohybrids indicates that during continuous operation, the CoNHs rebuild and regenerate in situ leading to the formation of two-dimensional nanostructures comprising a mixture of cobalt chalcogenides (Co 3 S 4 and CoS 2 ). The integration of the CoNHs in a quantum-dot based PEC cell and an alkaline electrolyzer (1 M KOH) demonstrates the versatility and viability of these alternative electrodes toward active and solar-driven fuel generation.