Photoelectron “Bridge” in Van Der Waals Heterojunction for Enhanced Photocatalytic CO₂ Conversion Under Visible Light

Constructing Van der Waals heterojunction is a crucial strategy to achieve excellent photocatalytic activity. However, in most Van der Waals heterojunctions synthesized by ex situ assembly, electron transfer encounters huge hindrances at the interface between the two components due to the large spacing and potential barrier. Herein, a phosphate-bridged Van der Waals heterojunction of cobalt phthalocyanine (CoPc)/tungsten disulfide (WS₂) bridged by phosphate (xCoPc-nPO₄⁻-WS₂) is designed and prepared by the traditional wet chemistry method. By introducing a small phosphate molecule into the interface of CoPc and WS₂, creates an electron “bridge”, resulting in a compact combination and eliminating the space barrier. Therefore, the phosphate (PO₄⁻) bridge can serve as an efficient electron transfer channel in heterojunction and can efficiently transmit photoelectrons from WS₂ to CoPc under excited states. These excited photoelectrons are captured by the catalytic central Co²⁺ in CoPc and subsequently convert CO₂ molecules into CO and CH₄ products, achieving 17-fold enhancement on the 3CoPc-0.6PO₄⁻-WS₂ sample compared to that of pure WS₂. Introducing a small molecule “bridge” to create an electron transfer channel provides a new perspective in designing efficient photocatalysts for photocatalytic CO₂ reduction into valuable products.