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

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Solar hydrogen evolution is a promising solution to the energy crisis.
• Noble metal-based photocatalysts are effective but costly and unsustainable.
• Developing efficient, earth-abundant photocatalysts is crucial.

Purpose of the Study:

• To design and synthesize a novel, highly active, and stable noble-metal-free photocatalyst for solar hydrogen production.
• To investigate the synergistic effects of a molecular complex cocatalyst and a modified carbon nitride support.
• To enhance visible light absorption and charge separation efficiency.

Main Methods:

• Synthesis of thiophene-embedded polymeric carbon nitride (TPCN).
• Covalent grafting of NiL2(Cl)2 molecular complex cocatalyst onto TPCN.
• Characterization of the hybrid catalyst (NiL2(Cl)2/TPCN).
• Evaluation of photocatalytic hydrogen production activity under visible light irradiation (λ ≥ 420 nm).

Main Results:

• The NiL2(Cl)2/TPCN hybrid catalyst achieved a high H2 production rate of 95.8 μmol h⁻¹ without platinum.
• An apparent quantum yield of 6.68% at 450 nm was observed.
• Thiophene incorporation extended π-conjugation and enhanced visible light absorption.
• Electron-withdrawing effect of thiophene and CN covalent bonds facilitated charge separation and electron transfer to Ni active sites.

Conclusions:

• Embedding π-electron-rich compounds like thiophene into graphitic carbon nitride is an effective strategy for developing superior photocatalysts.
• The strong covalent linkage between molecular cocatalysts and organic semiconductors is key for noble-metal-free photocatalyst design.
• This work presents a significant advancement in creating stable, highly active, noble-metal-free photocatalysts for visible-light-driven hydrogen evolution.