Self-Supporting Triphase Photocatalytic CO 2 Reduction to CH 3 OH on Controllable Core-Shell Structure with Tunable Interfacial Wettability.

Enhancing the CO 2 mass transfer and proton supply in the photocatalytic reduction of CO 2 with H 2 O into CH 3 OH (PRC-M), while avoiding the hydrogen evolution reaction (HER), remains a challenge. Herein, we propose an approach to control the surface coverage of CO 2 and H 2 O by modifying interfacial wettability, which is achieved by modulating the core-shell structure to expose either hydrophobic melamine-resorcinol-formaldehyde (MRF) or hydrophilic NiAl-layered double hydroxides (NAL). Characterizations reveal that an insufficient proton supply leads to the production of competing CO, while excessive coverage of H 2 O results in undesired HER. The NAL-MRF integrates hydrophobic and hydrophilic interfaces, contributing to the CO 2 mass transfer and H 2 O adsorption, respectively. This combination forms a microreactor that facilitates the triphase photocatalysis of CO 2 , H 2 O, and catalyst, allowing for high local concentrations of both *CO and *H without competing binding sites. Importantly, the formation of covalent bonds and a Z-type heterojunction between hydrophilic NAL and hydrophobic MRF layers accelerates the charge separation. Furthermore, the density functional theory results indicate that the NAL linking promotes the continuous hydrogenation of *CO. As a result, an enhanced CH 3 OH yield of 31.41 μmol g -1 h -1 , with selectivity of 93.62%, is achieved without hole scavengers or precious metals.