Cobalt-induced asymmetric electron distribution boosts photocatalytic hydrogen production efficiency

Hydrogen production from solar-driven water splitting serves as a crucial technology to sustainably access zero-carbon H2 energy. Toward large-scale application, cost-effective cocatalysts—such as transition metal sulfides—with high H2 evolution activity and excellent stability are desperately needed to greatly boost the solar-to-hydrogen conversion efficiency. Unfortunately, the intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates (Had) to form strong S-Had bonds, resulting in a low photocatalytic H2 evolution activity. Although introducing vacancies, integrating semiconductors/metals or doping heteroatoms have been proposed to improve the H2 evolution kinetics on active S atoms, the underlying regulation mechanism of the weakened S-Had bonds is still ambiguous. Therefore, developing an effective strategy to break the symmetrical electron distribution of transition metal sulfides and disclose its underlying regulation mechanism on weakening S-Had bonds are highly meaningful.

Recently, a research team led by Prof. Yaorong Su (Shenzhen Technology University, Shenzhen, China) demonstrated that cobalt-induced asymmetric electronic distribution is an effective strategy for optimizing the electronic configuration of sulfur sites in NiCoS cocatalysts. This approach achieved highly efficient photocatalytic hydrogen evolution. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64747-4).

Co atoms could be uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO2 surface by a facile photosynthesis strategy. Experimental and theoretical data systematically disclosed that the larger electronegativity difference between Co and S atoms induces an directional electron transfer from Co to S, thus resulting in charging the p-orbital of S atoms and formation of electron-enriched S(2+δ)- sites, which weakens the S(2+δ)--Had bonds for accelerating the interfacial H2 evolution dynamics of the NiCoS cocatalysts. Furthermore, the in-situ X-ray photoelectron spectroscopy and Femtosecond transient absorption spectroscopy concurrently revealed that the NiCoS cocatalysts also serve as an efficient channel for rapidly transferring photogenerated electrons from the host TiO2. Encouragingly, the optimal NiCoS/TiO2(1:2) photocatalyst exhibited an enhanced H2 production activity of 2702.96 μmol g-1 h-1, realizing 2.1- and 2.5-fold enhancements than that of NiS/TiO2 and CoS/TiO2, respectively. This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.

About the journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 17.7.

At Elsevier http://www.journals.elsevier.com/chinese-journal-of-catalysis

Manuscript submission https://mc03.manuscriptcentral.com/cjcatal

END