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Issue 20, 2020
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Inserting Co and P into MoS2 photocathodes: enhancing hydrogen evolution reaction catalytic performance by activating edges and basal planes with sulfur vacancies

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Abstract

The production of hydrogen using solar energy via a photoelectrochemical system is an effective technique for meeting present clean energy needs. Owing to the small bandgap and highly negative conduction band edge (−0.46 V) of Si, it is considered a promising photocathode material for solar hydrogen evolution reaction (HER). However, because of sluggish HER kinetics on the Si surface, bare Si electrodes have a high overpotential. Molybdenum disulfide (MoS2) has attracted wide interest as a promising alternative to Pt-based catalysts for producing hydrogen. Nevertheless, it suffers from sluggish kinetics for driving the process of HER because of its inert basal plane. Herein, HER performance was enhanced by doping a metal (cobalt) and a nonmetal (phosphorus) into MoS2. Doping MoS2 (CoPO-MoS2) on Si photocathodes with cobalt and phosphorous provides a current density of about 21.6 mA cm−2 at 0 V (vs. RHE) and a reduced Tafel value of 54.3 mV dec−1. The doped catalyst shows good stability up to 3 h with retention of about 85%. The flat surface of the Si photocathode has been chemically etched into pyramidal structures (SiMP) to reduce the loss due to reflection and enhance the catalytically active surface. Raman, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure reveal that Co and P strongly coordinated with the MoS2 materials. Furthermore, the catalytic performance was enhanced by the defect sites on MoS2, thereby stimulating more S vacancies on the basal planes and S-edge sites. Defect engineering will hopefully provide a new research direction for the innovation and development of more active sites of CoPO–MoS2.

Graphical abstract: Inserting Co and P into MoS2 photocathodes: enhancing hydrogen evolution reaction catalytic performance by activating edges and basal planes with sulfur vacancies

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Supplementary files

Article information


Submitted
16 Jun 2020
Accepted
29 Jul 2020
First published
07 Aug 2020

Catal. Sci. Technol., 2020,10, 6902-6909
Article type
Paper

Inserting Co and P into MoS2 photocathodes: enhancing hydrogen evolution reaction catalytic performance by activating edges and basal planes with sulfur vacancies

K. Pichaimuthu, A. Jena, H. Chang, C. Su and R. Liu, Catal. Sci. Technol., 2020, 10, 6902
DOI: 10.1039/D0CY01205J

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