Christos Dimitriou, Christos Gkatziouras, Elodie Gioan, Maria Louloudi, Johan G. Alauzun, Yiannis Deligiannakis
Formic acid dehydrogenation (FADH) is a highly potent strategy for industrial-scale H2 production at near-ambient P and T; thus, development of efficient heterogeneous catalysts capable of promoting FADH is a forward-looking challenge. Herein, we demonstrate a molecular surface-engineering approach to tailor anatase-TiO2 quantum dots (TiO2-QDs) through covalent grafting of phosphonate ligands, bearing either imidazolium (Im) or diphenylphosphine (Phos) functionalities. Controlled surface functionalization was achieved via phosphonate anchoring, using either hydrothermal or microwave-assisted grafting, enabling tuning of the organic–inorganic interface. Beyond serving as surface modifiers, the phosphonate ligands regulate the local chemical environment of TiO2 by modifying the interfacial electronic structure and the distribution of catalytically accessible surface sites. Using Fe(ii) as the metal catalytic center, the optimized TiO2-QD-Phos/Fe hybrid catalyst achieves H2 production/FADH performance with TON = 4580 and TOF = 3915 h−1. Spectroscopic and structural data allow comprehension of the roles of TiO2-QDs, grafting methodology, and ligand functionality as the key factors that dictate structure–activity relationships. Catalytic H2 production performance of TiO2-QD-Phos/Fe and TiO2-QD-Im/Fe originates from a synergistic interplay between TiO2 surface chemistry and the molecular architecture of the grafted phosphonate ligands. The present work establishes phosphonate ligand engineering as a versatile strategy for controlling oxide surface reactivity and provides a general design platform for developing high-performance heterogeneous catalysts for H2 generation from liquid organic hydrogen carriers.