Photocatalytic hydrogen (H2) production from
ethanol offers the dual advantages of low energy consumption
and the cogeneration of high-value chemicals. However, challenges
remain in enhancing product selectivity and elucidating the precise
reaction pathway. In this study, lead-free halide perovskites CsGeX3
(X = Cl, Br, I) were synthesized and utilized for the simultaneous
generation of H2 and acetaldehyde via photocatalytic ethanol
oxidation under UV and visible light irradiation. Among them,
CsGeI3 is reported for the first time as a highly effective
photocatalyst, exhibiting the highest activity for both the hydrogen
evolution reaction (HER) and the ethanol oxidation reaction
(EOR). Under UV light irradiation for 3 h, CsGeI3 achieves H2 and
acetaldehyde yields of 97.74 and 92.08 μmol g− 1, respectively, with
an apparent quantum yield (AQY) of 2.31% for H2. Optical characterization and density functional theory (DFT) calculations
revealed that the Lewis acid−base properties of CsGeI3 are mainly governed by the halogen component, enabling the selective
activation and cleavage of the α-C−H and O−H bonds in ethanol, promoting heterolytic reactions that enhance the formation of
both H2 and acetaldehyde. This study provides new insights into the application of lead-free halide perovskites in tunable solar fuel
generation and selective value-added chemical synthesis.