Well-defined Cu$_2$O photocatalysts for solar fuels and chemicals

TL;DR

This review discusses the synthesis, properties, and photocatalytic applications of well-defined Cu$_2$O nanostructures, highlighting recent advances, challenges in stability, and future directions for solar fuel and chemical production.

Contribution

It provides a comprehensive overview of facet engineering, hybrid structures, and strategies to improve efficiency and stability of Cu$_2$O photocatalysts for sustainable energy applications.

Findings

Facet-dependent photocatalytic activity identified.

Hybrid Cu$_2$O structures enhance performance.

Strategies proposed to improve photostability.

Abstract

The shape-controlled synthesis of cuprous oxide (Cu$_2$O) photocatalysts with both low or high index crystal planes has received increasing attention due to their unique facet-dependent properties. Since they are cheap and earth abundant, these well-defined Cu$_2$O nanostructures are extensively used for different photocatalytic reactions, also because of their strong visible light absorption capability. However, further development will be still needed to enhance the efficiency and photostability of Cu$_2$O, which still limits its industrial application. We start this review by summarizing the synthetic advancement in the facet engineering of Cu$_2$O and other associated hybrid Cu$_2$O-based heterostructures with a special emphasis put on their growth mechanism. We then discuss different facet-dependent properties, which are relevant to photocatalysis. In the subsequent section, we present a critical discussion on the photocatalytic performance of faceted Cu$_2$O nanostructures during organic synthesis, hydrogen production, and carbon dioxide photoreduction. The relation between photocatalytic efficiency and product selectivity with exposed crystal facets or with different composition of hybrid nanostructures is also discussed. Finally, important strategies are proposed to overcome the photostability issue, while outlining the course of future development to further boost the technological readiness of well-defined Cu$_2$O-based photocatalysts.