Work

Ni/TiO 2 Interfaces Enhance Benzaldehyde Selectivity in the Photocatalytic Dehydrogenation of Benzyl Alcohol

Year: 2026

Type: preprint

Abstract: The selective conversion of alcohols to carbonyls (ketones and aldehydes) plays an important role in chemical manufacturing. Photocatalytic acceptorless dehydrogenation offers a light-driven alternative for producing value-added aldehydes and H 2 under mild conditions and with easy separation and high molar efficiency. However, using semiconductor photocatalysts to achieve high selectivity and long-term stability under prolonged high-intensity illumination remains challenging. In this work, we developed CdS/TiO 2 /Ni photocatalysts by depositing TiO 2 onto CdS nanoparticle panels via atomic layer deposition (ALD), followed by Ni cocatalyst photodeposition, for the acceptorless dehydrogenation of benzyl alcohol to benzaldehyde and H 2 . Diluting the benzyl alcohol concentration to a practical range of ~10 vol% (1 M) further increased benzaldehyde selectivity to ~95%. Ni photodeposition and zeta-potential measurements suggest that TiO 2 coatings progressively modify Cd 2+ -associated surface sites through Ti 3+ /Ti 4+ incorporation, altering adsorption kinetics and contributing to the reduced activity. This extends the photocatalyst’s lifespan from ~23 to 60 hours and increases cumulative benzaldehyde and H 2 production. TiO 2 thin-film coatings have emerged as a promising strategy to protect semiconductor photocatalysts while modifying surface active sites and reaction kinetics, and their stability-activity trade-off showing lower initial-stage activity beyond 15-cycle ALD will be discussed alongside proposed mechanisms. This work establishes a semiconductor/coating/cocatalyst design architecture that highlights the importance of engineering surface adsorption and active-site environments, alongside charge-separation strategies based on band-edge energetics and charge-carrier dynamics, to jointly optimize photocatalytic activity and product selectivity for targeted chemical synthesis.

Source: ChemRxiv

DOI: 10.26434/chemrxiv.15011181/v1