Photocatalytic Upgrade of Primary Alcohols to Value-Added Aldehydes by Carbon Nitride and Related Systems.

The solar-driven photocatalytic oxidation of primary alcohols to aldehydes has emerged as a sustainable route for chemical manufacturing, offering an environmentally friendly alternative to conventional thermal and metal-catalyzed methods that rely on harsh conditions and toxic oxidants. Among reported systems, polymeric carbon nitride (PCN) has demonstrated exceptional selectivity toward value-added aldehydes, including formaldehyde, acetaldehyde, glyceraldehyde, and benzaldehyde. This work reviews recent progress in PCN-based photocatalysts for upgrading methanol, ethanol, glycerol, and benzyl alcohol, with emphasis on modification strategies, including catalyst design and engineering that promote charge separation and surface reactivity, often achieving near-quantitative selectivity. Despite these advances, low product yields remain a challenge, limited by sluggish carrier dynamics, narrow light absorption, and surface kinetics. We further highlight emerging detection techniques, mechanistic insights, and future directions to bridge selectivity with productivity for scalable solar-driven synthesis.