Decorating SrTiO ₃ With Cu@Pt Core‐Shell Cocatalysts to Promote the Selective Thermally Assisted Photocatalytic Methanol Dehydrogenation to Formaldehyde

Photocatalytic methanol conversion, a process of particular interest in the context of hydrogen generation, also holds promise as a sustainable approach to chemical synthesis of value‐added products, including formaldehyde. In this study, Cu‐core/Pt‐shell modified SrTiO ₃ photocatalysts are demonstrated to enhance the thermally assisted photocatalytic methanol dehydrogenation in the gas phase by 50% compared to Pt/SrTiO ₃ photocatalysts prepared by conventional photodeposition, while maintaining a high formaldehyde selectivity. Cu‐core/Pt‐shell structures were prepared by means of galvanic displacement, in which Cu is displaced by Pt, yielding irregular core–shell structures consisting of hexagonal Pt particles. These particles transform during extended operation into smooth core–shell systems, thereby enabling stable methanol dehydrogenation. Initial deactivation of the samples is associated with CO‐induced Pt reconstruction, as evidenced by operando diffuse reflectance infrared Fourier transform spectroscopy and transmission electron microscopy. Despite this initial deactivation, the photocatalytic performance is found to be attributable to a significantly enhanced charge separation and carrier lifetime. This enhancement is presumed to be the result of the formation of an Ohmic contact between the SrTiO ₃ absorber and Cu, thereby, enabling efficient charge transfer to the catalytically active Pt surface. This study underscores the beneficial properties of core–shell cocatalysts and highlights the potential for value‐added chemical production using photocatalysis in the gas phase.