Issue 19, 2021

A well-designed honeycomb Co3O4@CdS photocatalyst derived from cobalt foam for high-efficiency visible-light H2 evolution

Abstract

Well-designed honeycomb Co3O4@CdS (H-Co3O4@CdS) was fabricated via a one-step strategy for efficient water splitting. During the decoration of CdS, honeycomb Co3O4 (H-Co3O4) with macropores was formed simultaneously. H-Co3O4 could enhance CdS visible-light absorption capacity conspicuously and narrow its band gap from 2.08 to 1.03 eV. Therefore, H-Co3O4@CdS presented a remarkable H2 production of up to ca. 16 320 μmol g−1 h−1 (λ > 420 nm), nearly 7.3 times higher than that of pristine CdS, indicating the excellent synergistic effect between H-Co3O4 and CdS. Through various photoelectricity tests (e.g., PL spectra, EPR, photoelectric responsiveness and impedance), it could be found that the distinguished H2 evolution was attributed to the improved charge carrier separation and electron generation. What's more, the enhanced H2 production of H-Co3O4@CdS is related to the improved specific surface area (83.49 m2 g−1) and pore volume (0.247 cm3 g−1) as well. Density Functional Theory (DFT) calculations confirmed that CdS has the function of diverting electrons, and the orbital energy level of absorbed H2O molecules showed obvious migration due to the accumulation of electrons. Besides, the d-band of Co could induce more electrons to traverse the Fermi level. Subsequently, more electrons could be transferred from Co3O4 to CdS and break the O–H1 bond. Compared to the H-Co3O4@CdS system, the d-band center of the Co atoms in H-Co3O4@CdS–H2O shifted from −5.83 to −2.58 eV, thereby demonstrating that Co3O4 served as an electron reservoir for charge redistribution in the photocatalytic water splitting process. In the end, a practicable mechanism for H-Co3O4@CdS about H2O dissociation and H2 desorption was proposed.

Graphical abstract: A well-designed honeycomb Co3O4@CdS photocatalyst derived from cobalt foam for high-efficiency visible-light H2 evolution

Supplementary files

Article information

Article type
Paper
Submitted
24 Nov 2020
Accepted
20 Apr 2021
First published
20 Apr 2021

J. Mater. Chem. A, 2021,9, 11665-11673

A well-designed honeycomb Co3O4@CdS photocatalyst derived from cobalt foam for high-efficiency visible-light H2 evolution

C. Zhang, B. Liu, W. Li, X. Liu, K. Wang, Y. Deng, Z. Guo and Z. Lv, J. Mater. Chem. A, 2021, 9, 11665 DOI: 10.1039/D0TA11433B

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