Co1-xS/N-doped graphene foam composite as efficient bifunctional electrocatalysts for the evolution reaction of oxygen and hydrogen. (10th October 2021)

• Record Type: Journal Article
• Authors: Wang, Shuliang; Huang, Xin; Wu, Mingyu; Wang, Shidong; Liu, Li; Xiang, Ding-han
• Is Part Of: Electrochimica acta. Volume 393(2021)
• Publication Date: 2021-10-10
• Subjects: Transition metal sulfide -- Nitrogen-doped graphene foam -- Bifunctional electrocatalyst -- Water splitting -- Oxygen evolution reaction; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.139081
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: As an environment-friendly and sustainable energy conversion technology, water electrolysis is strongly dependent on the efficiency and cost of the electrocatalysts. Herein, nanosheet-constructed cobalt sulfide microspheres incorporated with nitrogen-doped graphene foam (Co1-x S/NGF), a highly efficient bifunctional electrocatalyst for overall water splitting, was obtained by controlled two-step synthesis. The nitrogen-doped graphene foam (NGF) underlying the Co1-x S microspheres provides an electrically conducting support for the catalysts, contributes small size and homogeneous distribution of the in-situ grown Co1-x S microspheres, and affords abundant active sites for fast and sufficient transport of mass and electrons and, therefore, highly enhanced catalytic activity through the strong synergistic effect of Co1-x S microspheres and the NGF substrate. In 1 M KOH, the Co1-x S/NGF hybrid catalyst exhibits remarkable OER and HER catalytic performance, with overpotentials of 233.6 mV for the OER and 163.7 mV for the HER at 10 mA cm −2, and the corresponding Tafel slopes of 138 and 95 mV dec −1, respectively. The hybrid material of Co1-x S/NGF even exhibits a lower overpotential (η20 ) to reach 20 mA cm −2 towards OER than that of RuO2, and its performance matches the best cobalt sulfide bifunctional electrocatalysts reported to date. Besides, the Co1-x S/NGF is highly stable for long-term water electrolysis in the 1 M KOH. These findings support that the current Co1-x S/NGF is a competitive candidate of transition metal-based catalysts for cost-efficient and large-scale overall water electrolysis in the alkaline environment. Highlights: Nanosheet-constructed cobalt sulfide microspheres anchored N-doped graphene foam (Co1-x S/NGF) was synthesized. It exhibited remarkable OER catalytic activity with an overpotential of 233.6 mV at 10 mA cm −2 . Annealing was vital in reducing the size and controlling the distribution of the Co1-x S particles on NGF substrate.