Issue 12, 2022

Bimetallic Co–Mo sulfide/carbon composites derived from polyoxometalate encapsulated polydopamine-decorated ZIF nanocubes for efficient hydrogen and oxygen evolution

Abstract

The increased call for carbon neutrality by 2050 makes it compelling to develop emission-free alternative energy sources. Green hydrogen produced from water electrolyzers using renewable electricity is of great importance, and the development of efficient transition-metal-based materials for hydrogen production by electrolysis is highly desirable. In this report, a new approach to produce defect-rich and ultra-fine bimetallic Co–Mo sulfides/carbon composites from polyoxometalates@ZIF-67@polydopamine nanocubes via carbonization/sulfurization, which are highly active for hydrogen and oxygen evolution reactions (HER and OER), have been successfully developed. The coating of polydopamine (PDA) on the surface of the acid-sensitive ZIF-67 cubes can prevent the over-dissociation of ZIF-67 caused by the encapsulated phosphomolybdic acid (PMA) etching through PDA chelating with the PMA molecules. Meanwhile, the partially dissociated Co2+ from ZIF-67 can be captured by the coated PDA via chelation, resulting in more evenly dispersed active sites throughout the heterogeneous composite after pyrolysis. The optimized bimetallic composite CoMoS-600 exhibits a prominent improvement in HER (with an overpotential of −0.235 V vs. RHE at a current density of 10 mA cm−2) and OER performance (with an overpotential of 0.350 V vs. RHE at a current density of 10 mA cm−2), due to the synergistic effect of ultra-fine defect-rich Co–Mo–S nanoparticle active sites and N,S-codoped porous carbons in the composites. Moreover, this synthesis approach can be readily expanded to other acidic polyoxometalates to produce HER and OER active bimetallic Co–W sulfide/carbon composites by replacing PMA with phosphotungstic acid. This new synthesis strategy to modify acid-sensitive ZIFs with selected compounds offers an alternative approach to develop novel transition metal sulfide/carbon composites for various applications.

Graphical abstract: Bimetallic Co–Mo sulfide/carbon composites derived from polyoxometalate encapsulated polydopamine-decorated ZIF nanocubes for efficient hydrogen and oxygen evolution

Supplementary files

Article information

Article type
Paper
Submitted
01 Dec. 2021
Accepted
22 Febr. 2022
First published
23 Febr. 2022
This article is Open Access
Creative Commons BY license

Nanoscale, 2022,14, 4726-4739

Bimetallic Co–Mo sulfide/carbon composites derived from polyoxometalate encapsulated polydopamine-decorated ZIF nanocubes for efficient hydrogen and oxygen evolution

Z. Huang, Z. Yang, Q. Jia, N. Wang, Y. Zhu and Y. Xia, Nanoscale, 2022, 14, 4726 DOI: 10.1039/D1NR07913A

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