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Abstract

Herein, composites of nanosheets with van der Waals contacts are employed to disclose how the interlayer-microenvironment affects the product selectivity of carbon dioxide (CO₂) photoreduction. The concept of composites of nanosheets with dual active sites is introduced to manipulate the bonding configuration and promote the thermodynamic formation of methanol (CH₃OH). As a prototype, the CoNi₂S₄–In₂O₃ composites of nanosheets are prepared, in which high-resolution transmission electron microscopy imaging, X-ray photoelectron spectroscopy spectra, and zeta potential tests confirm the presence of van der Waals contacts rather than chemical bonding between the In₂O₃ nanosheets and the CoNi₂S₄ nanosheets within the composite. The fabricated CoNi₂S₄–In₂O₃ composites of nanosheets exhibit the detection of the key intermediate *CH₃O during CO₂ photoreduction through in situ Fourier transform infrared spectra, while the In₂O₃ nanosheets and CoNi₂S₄ nanosheets alone do not show this capability, further verified by the density functional theory calculations. Accordingly, the CoNi₂S₄–In₂O₃ composites of nanosheets show the ability to produce CH₃OH, whereas the CoNi₂S₄ and In₂O₃ nanosheets solely generate carbon monoxide products from CO₂ photoreduction.