Bidirectional Heterojunctions Photocatalyst Engineered with Separated Dual Reduction Sites for Hydrogen Evolution

Photocatalytic technology is identified as one of the most clean and sustainable routes for hydrogen generation. Nonetheless, inadequate photoinduced carrier separation limits photocatalytic performance. Rationally designing bidirectional heterojunctions that leverage single/two-photon co-excitation pathways and dual reduction sites, thereby inhibiting recombination of the photoinduced carriers and exposing active sites to increase photocatalytic activity. This study proposes bidirectional heterojunctions consisting of 0D carbon dots (CDs) and nickel phthalocyanines co-modified sulfur-doped multivesicular carbon nitride tubes (denoted as 7CDs/SMVCTs/Ni0.5%). The as-prepared photocatalyst displays a remarkable yield of 16363.62 μmol g−1 h−1, with a rate 23.2 times that of pristine carbon nitride (denoted as PCN, 704.23 μmol g−1 h−1). The improvement of photocatalytic performance is attributed to the efficient separation and transportation of photoexcited electron-hole pairs induced by the coexistence of single/two-photon excitation pathways and dual reduction sites. The efficient combination of lateral and vertical heterostructures plays an essential role in the photocatalytic process and is exhaustively studied using catalyst rational design and modification technology.