Cu2O/SnO2 Heterostructures: Role of the Synthesis Procedure on PEC CO2 Conversion

Addressing the urgent need to mitigate increasing levels of CO₂ in the atmosphere and combat global warming, the development of earth-abundant catalysts for selective photo-electrochemical CO₂ conversion is a central and pressing challenge. Toward this purpose, two synthetic strategies for obtaining a Cu₂O–SnO₂ catalyst, namely co-precipitation and core–shell methods, were compared. The morphology and band gap energy of the synthesized materials were strongly different. The photoactivity of the core–shell catalyst was improved by 30% compared to the co-precipitation one, while its selectivity was shifted towards C₁ products such as CO and formate. The stability of both catalysts was revealed by an easy and fast EIS analysis, indicating how the effective presence of a SnO₂ shell could prevent the modification of the crystalline phase of the catalyst during PEC tests. Finally, directing the selectivity depending on the synthesis method used to produce the final Cu₂O–SnO₂ catalyst could possibly be implemented in syngas and formate transformation processes, such as hydroformylation or the Fischer–Tropsch process.