What is it about?
It is of vital importance to design efficient and low-cost bifunctional catalysts for the electrochemical water splitting under alkaline and neutral pH conditions. In this work, we report an efficient and stable NiCo2S4/N, S co-doped reduced graphene oxide (NCS/NS-rGO) electrocatalyst for water splitting, in which NCS microspheres are composed of one-dimentional (1D) nanorods grown homogeneously on the surface of NS-rGOs). The synergetic effect, abundant active sites, and hybridization of NCS/NS-rGO endow their outstanding electrocatalytic performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both alkaline and neutral conditions. Furthermore, NCS/NS-rGO employed as both anode and cathode in a two-electrode alkaline and neutral system electrolyzers deliver 10 mA/cm2 with the low cell voltage of 1.58 V in alkaline and 1.91 V in neutral condition. These results illustrate the rational design of carbon-supported nickel-cobalt based bifunctional materials for practical water splitting over a wide pH range.
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Why is it important?
Herein, we synthesize a novel hierarchical porous NCS/NSrGO composite using thiourea as the N as well as S source and precipitant, where NCS microspheres assembled with 1D nanorods are uniformly grown onto the NS-rGO surface (Scheme 1). The multiple microstructures and N, S co-doping expose abundant active sites, meanwhile, the synergetic effect of NCS/NS-rGO increase the catalytic efficiency of active sites and charge transfer for improving their electrocatalytic performance. Based on the above combined advantages, NCS/NS-rGO exhibits outstanding OER and HER activities in the neutral and alkaline electrolytes. The electrocatalytic mechanism of NCS/NS-rGO is further revealed via the electrochemical active surface area (ECSA) and turnover frequency (TOF). The superior electrocatalytic activity of NCS/NS-rGO is of great significance for the development of economical and feasible overall water splitting in neutral and alkaline systems.
Perspectives
In conclusion, NCS/NS-rGO is successfully synthesized by one-pot hydrothermal method. NCS microspheres assembled with nanorods are evenly anchored on the surface of NS-rGO due to the specific microstructure of N, S co-doped rGO. The synthetic effect between NCS and NS-rGO as well as N, S codoping can effectively improve the conductivity and electronic microstructure of NCS/NS-rGO, which enhances the electron transport ability and the electrocatalytic performance. NCS/NSrGO shows outstanding HER and OER catalytic performance with a trace loading of 0.1 mg/cm2 in alkaline and neutral pH electrolyte and the electrocatalytic mechanism of NCS/NSrGO is systematically clarified. Therefore, NCS/NS-rGO can be used as a promising electrocatalyst for practical overall water splitting devices for large scale hydrogen production.
Long Chen
Shihezi University
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This page is a summary of: NiCo2S4 microspheres grown on N, S co-doped reduced graphene oxide as an efficient bifunctional electrocatalyst for overall water splitting in alkaline and neutral pH, Nano Research, July 2021, Tsinghua University Press,
DOI: 10.1007/s12274-021-3580-z.
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