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Supplementary information files for "S-scheme p-n junction Na0.6CoO2/g-C3N4 heterostructure as an efficient photocatalyst for green hydrogen production: fabrication, characterization and mechanisms"

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posted on 2025-01-21, 16:24 authored by Wen-Feng LinWen-Feng Lin, Yan Wu, Shumail Farhan, Yang YanYang Yan

Supplementary information files for article "S-scheme p-n junction Na0.6CoO2/g-C3N4 heterostructure as an efficient photocatalyst for green hydrogen production: fabrication, characterization and mechanisms"

Probing the spatial separation and transport process of photogenerated charges at nanoscale interfaces is essential for understanding catalytic reaction mechanisms on heterostructure photocatalysts. Here, we developed a p-n junction Na0.6CoO2/g-C3N4 S-scheme photocatalyst via electrostatic self-assembly technology. A significant hydrogen production rate of ∼ 0.294 mmol g−1 h−1 was achieved on the optimal Na0.6CoO2/g-C3N4, which was ten times higher than that of pure g-C3N4. In-situ XPS shows that the electrons in Na0.6CoO2/g-C3N4 had different flow directions without and with illumination, demonstrating a built-in electric field being formed through Na0.6CoO2 and g-C3N4 interaction. DFT calculations and ultraviolet photoelectron spectroscopy verified that g-C3N4 and Na0.6CoO2 possess the energy band structures conforming to the heterostructure of S-scheme. In-situ Kelvin probe microscope studies show that Na0.6CoO2 and g-C3N4 both have a self-induced electric field effect, and their combination significantly strengthens the built-in electric field and improves the space separation of photogenerated electrons. Compared with the change of the surface photovoltage of g-C3N4 (60 mV) and Na0.6CoO2 (−30 mV), the average surface contact potential difference of Na0.6CoO2/g-C3N4 reached 320 mV, yielding a higher efficiency of photogenerated electron separation. This work also provides direct evidence on the existence of a built-in electric field and an electron flow direction for heterostructure photocatalyst materials.

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Funding

National Natural Science Foundation of China (NSFC Grant No. 22378372)

Sustainable Hydrogen Production from Seawater Electrolysis

Engineering and Physical Sciences Research Council

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Newton Advanced Fellow ship award (NAF\R1\191294)

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