Alkene hydroformylation with syngas (CO + H₂) to produce aldehydes is one of the most important chemical reactions. However, designing heterogeneous catalysts to realize comparable performance with mature homogeneous catalysts is challenging. In this report, a reduced graphene oxide (RGO) supported rhodium nanoparticle (Rh/RGO) catalyst was successfully prepared via a one-pot liquid-phase reduction method and first applied in 1-hexene hydroformylation. 1-Hexene hydroformylation reaction under different reaction conditions with this Rh/RGO catalyst was investigated in detail. Low reaction temperature and short reaction time effectively enhanced the n/i (normal to iso) ratio of heptanal in the products. The catalytic performance of the Rh/RGO catalyst was also compared with those of Rh supported on other carbon materials, including activated carbon and carbon nanotubes (Rh/AC and Rh/CNTs). The results showed that the Rh/RGO catalyst exhibited the highest 1-hexene conversion and the largest n/i ratio of 4.0 among the tested catalysts. The special 2D nanosheet structure of the Rh/RGO catalyst, rather than the 3D porous and 1D nanotube structures of Rh/AC and Rh/CNTs, respectively, principally contributed to its excellent catalytic performance. These findings disclosed that reduced graphene oxide could be a promising catalyst support for designing heterogeneous hydroformylation catalysts.

Photocatalysis plays a vital role in sustainable energy conversion and environmental remediation because of its economic, eco-friendly, and effective characteristics. Nitrogen-rich graphitic carbon nitride (g-C₃N₅) has received worldwide interest owing to its facile accessibility, metal-free nature, and appealing electronic band structure. This review summarizes the latest progress for g-C₃N₅-based photocatalysts in energy and environmental applications. It begins with the synthesis of pristine g-C₃N₅ materials with various topologies, followed by several engineering strategies for g-C₃N₅, such as elemental doping, defect engineering, and heterojunction creation. In addition, the applications in energy conversion (H₂ evolution, CO₂ reduction, and N₂ fixation) and environmental remediation (NO purification and aqueous pollutant degradation) are discussed. Finally, a summary and some inspiring perspectives on the challenges and possibilities of g-C₃N₅-based materials are presented. It is believed that this review will promote the development of emerging g-C₃N₅-based photocatalysts for more efficiency in energy conversion and environmental remediation.