Flat meets functional: face-to-face 2D/2D S-scheme photocatalysts for efficient CO2-to-fuel conversion

Abstract

The rapidly increasing levels of atmospheric CO₂ have intensified the demand for sustainable carbon mitigation technologies. Among various approaches, photocatalytic CO₂ reduction (PCO₂R) has emerged as a compelling solar-driven route to transform CO₂ into value-added chemical fuels. This review systematically summarizes the recent progress in the rational design and fabrication of face-to-face 2D/2D S-scheme heterostructures for efficient PCO₂R. Specific attention is devoted to the internal electric field (IEF), band alignment, and interfacial engineering to facilitate directional charge separation and suppress recombination losses. The synergistic interactions within diverse 2D/2D heterostructures, including metal oxides, sulphides, and carbon-based materials, are elucidated through insights from advanced in situ characterization techniques, including X-ray photoelectron spectroscopy (XPS), Kelvin probe force microscopy (KPFM), and density functional theory (DFT) studies. Furthermore, this review outlines the possible future directions, highlighting opportunities in theoretical modelling, tandem catalysis systems, scalable synthesis strategies, and integrated multifunctional applications that couple CO₂ conversion with environmental remediation. This comprehensive overview provides a scientific foundation and practical roadmap for the strategic development of next-generation photocatalysts toward high-efficiency solar-to-chemical energy conversion.