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.