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Developing a cost-effective and multi-functional heterogeneous catalyst for various biomass transformations is important in both academic and industrial communities. Dehydration and oxidative dehydrogenation of biomass-based alcohols are fundamental transformations in both academic and industrial settings. However, due to the different catalytic mechanisms, using the same catalyst for regulating the selectivity of two reactions is a great challenge and has not been reported. In this work, we have pioneered the discovery of cheap and commercially available Zr(OH)4as a bifunctional heterogeneous catalyst for the selective transformation of biomass platform molecular 1-phenylethanol to acetophenone or styrene without any additives. Control experiments and DFT calculations revealed that the terminal and bridging hydroxyl groups of Zr(OH)4are the active sites for catalytic oxidative dehydrogenation and dehydration of 1-phenylethanol, respectively. As far as we know, this is the first report that simultaneously achieves the oxidative dehydrogenation and dehydration of alcohol by the same catalyst. This study proves the unique capabilities of the hydroxyl sites of Zr(OH)4and would help to design a multi-functional catalyst for the regulation of reaction selectivity.

The employment of stoichiometric alcohols and amines for imine synthesis under mild and green reaction conditions is still a challenge in the field. In this work, based on our research foundation in the thermocatalytic synthesis of imines over ceria, a CdS/CeO2heterojunction photocatalyst was constructed and successfully realized the atom-economic synthesis of imines under visible light without additives at room temperature. Mechanistic experiments and corresponding characterizations indicated that the CdS/CeO2heterojunction can improve the separation efficiency of photogenerated carriers, which can be further enhanced by the Ce4+/Ce3+redox pair by rapidly combining photogenerated e–. The in situ-reduced Ce3+can better activate O2to form Ce–O–O·, which, together with h+, efficiently accelerates alcohol oxidation, which is the rate-determined step for the synthesis of imines via oxidative coupling reaction of alcohol and amine. In addition, our photocatalyst exhibited fairly decent reusability and substrate universality. This work solves problems of using base additives and excess amine or alcohol in the reported photocatalytic systems and provides new insight for designing CeO2-based photocatalytic oxidation catalysts.