Visible Light‐Driven Acetaldehyde Production from CO ₂ and H ₂ O via Synergistic Vacancies and Atomically Dispersed Cu Sites

Abstract Acetaldehyde (CH 3 CHO) is of great industrial importance and serves as a key intermediate in various organic transformations. Photocatalytic production of acetaldehyde from CO 2 represents a sustainable route compared to conventional oxidation processes. However, current photocatalytic systems often face challenges, including limited product selectivity and dependence on sacrificial reagents. Here, we present a Cd 0.6 Zn 0.4 S (CZS) photocatalyst co‐modified with sulfur vacancies and atomically dispersed Cu (Cu/CZS−Vs) for the efficient conversion of CO 2 to acetaldehyde. Charge density analysis reveals that sulfur vacancies induce charge accumulation around the adjacent metal atoms, creating active sites that strongly anchor CO 2 and H + , thereby promoting CO 2 conversion while suppressing the competing hydrogen evolution reaction. The atomically dispersed Cu sites facilitate the conversion of key intermediates (i.e., *CHO and *CO) to the crucial C 2 intermediate *OCCHO, which can subsequently be converted to acetaldehyde. As a result, this catalyst achieves an acetaldehyde yield of 121.5 μmol g −1 h −1 with a selectivity of ca. 80 % via photocatalytic CO 2 conversion in the absence of sacrificial agents, along with a quantum efficiency of ca. 0.53 % at 400 nm, underscoring its potential for practical CO 2 conversion applications. These results are expected to pave the way for future developments in green chemical processes.