Photocatalytic HO Production with >30% Quantum Efficiency via Monovalent Copper Dynamics

Area of Science:

• Materials Science
• Catalysis
• Green Chemistry

Background:

• Photocatalytic oxygen reduction to hydrogen peroxide (H2O2) offers a sustainable and cost-effective alternative for chemical synthesis.
• Current methods face challenges with selectivity and efficiency due to limitations in the two-electron oxygen reduction reaction (ORR) pathway.

Purpose of the Study:

• To enhance photocatalytic H2O2 production by anchoring isolated Cu atoms with tunable oxidation states onto WO3.
• To investigate the role of Cu oxidation states in O2 adsorption, activation, and the *OOH intermediate hydrogenation for improved ORR selectivity.

Main Methods:

• Synthesis of isolated Cu atoms anchored on WO3 (Cu-SA/WO3) with controlled oxidation states.
• Experimental characterization and theoretical analysis (e.g., DFT calculations) to understand reaction mechanisms.
• Photocatalytic testing under visible light irradiation to measure H2O2 production rates and apparent quantum efficiency.

Main Results:

• Cu-SA/WO3 exhibited a loading-dependent transition of Cu oxidation states between +2 and +1.
• Cu(I) sites demonstrated superior O2 adsorption and activation, converting an unfavorable hydrogenation step into an exothermic process.
• Achieved a H2O2 production rate of 102 μmol h⁻¹ and an apparent quantum efficiency of 30% at 420 nm.

Conclusions:

• Anchoring isolated Cu atoms with modulated electronic states on WO3 is an effective strategy for enhancing photocatalytic H2O2 synthesis.
• Cu(I) single atoms play a crucial role in improving the selectivity and efficiency of the two-electron ORR pathway.
• This work offers new design principles for single-atom catalysts in sustainable H2O2 production.