Photocatalytic hydrogen evolution over a nickel complex anchoring to thiophene embedded g-C3N4

Evolution of hydrogen from water by utilizing solar energy and photocatalysts is one of the most promising ways to solve energy crisis. However, designing a cost-effective and stable photocatalyst without any noble metals is of vital importance for this process. Herein, an extremely active molecular complex cocatalyst NiL2(Cl)(2) is successfully designed. After being covalently linked to thiophene-embedded polymeric carbon nitride (TPCN), the hybrid catalyst NiL2(Cl)(2)/TPCN exhibits extraordinary H-2 production activity of 95.8 mu mol h(-1) without Pt (lambda >= 420 nm), together with a remarkable apparent quantum yield of 6.68% at 450 nm. In such a composite catalyst, the embedded pi-electron-rich thiophene-ring not only extends the pi-conjugated system to enhance visible light absorption, but also promotes the charge separation through electron-withdrawing effect. It turns out that the C-N covalent bonds formed between NiL2(Cl)(2) and TPCN skeleton accelerate the transfer of electrons to the Ni active sites. Our finding reveals that the strategy of embedding pi-electron-rich compounds to graphitic carbon nitride provides potentials to develop excellent photocatalysts. The strong covalent combination of molecular complexes cocatalyst onto organic semiconductors represents an important step towards designing noble-metal-free photocatalysts with superior activity and high stability for visible light driven hydrogen evolution. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

The study successfully designed an extremely active molecular complex cocatalyst NiL2(Cl)(2), which, when covalently linked to thiophene-embedded polymeric carbon nitride (TPCN), showed exceptional hydrogen production activity. The results indicated that embedding pi-electron-rich thiophene-ring enhanced visible light absorption and promoted charge separation, leading to accelerated electron transfer and the potential development of excellent photocatalysts.