Sulfur-Tolerant Nitroarene Hydrogenation over PtNi/TiO2 Catalysts via Coupled Heterolytic H2 Activation and Hydrogen Spillover

Abstract Sulfur poisoning is a critical bottleneck for noble-metal hydrogenation catalysts, severely hindering efficient production of high-value sulfur-containing fine chemicals like pharmaceutical intermediates. Conventional sulfur-tolerant strategies, electronic modulation to weaken sulfur adsorption and spatial confinement to isolate metal sites, both face an inherent activity−sulfur tolerance trade-off: electronic modification impairs H2 activation of metal sites, while spatial barriers reduce active site accessibility. Herein, we propose a hydrogen-mediated design strategy and fabricate a PtNi NPs/TiO2 catalyst with Ni-induced abundant surface oxygen vacancies, forming Ptδ+···OV···O2− interfacial motifs at the metal−support interface. The catalyst delivers 2.7-fold and 3.6-fold higher 4-nitroanisole hydrogenation activity than Pt1/TiO2 single-atom and Pt NPs/TiO2 references. Under thiophene poisoning, it shows only 14.8% deactivation with 48.9- and 11.9-fold activity margins; for sulfur-containing 4-nitrothioanisole, it achieves 78.8-fold and 4.6-fold higher activity with >99% target amine selectivity. DFT calculations and D2 isotope labeling among other experiments confirm that Ptδ+···OV···O2− interfacial motifs promote heterolytic H2 cleavage, generating reactive hydrogen for selective nitro group hydrogenation while reducing direct Pt site exposure to sulfur. Oxygen vacancies mediate hydrogen spillover to create extra surface sites, further shielding Pt centers. Their synergism breaks the inherent trade-off and establishes clear structure−performance correlations for rational sulfur-resistant catalyst design.