Conformal Titanyl Phosphate Surface Passivation for Enhancing Photocatalytic Activity

Abstract

A conformal titanyl phosphate passivation with the thickness of ca. 5 nm on the surface of TiO 2 nanoparticles for enhancing the photocatalytic degradation of organic pollutants and hydrogen production is described. The phosphate anion species bound to the surface of TiO 2 promote the favorable kinetics of photocatalytic activity and influence the catalytic reaction pathway. By using a facile surfactant-assisted sol-gel process, the surface defects of TiO 2 associated with deep traps was reduced and passivated by the phosphate anion species to form the titanyl phosphate. The strong bonds between the titanyl phosphate shell and TiO 2 core provided a long-term photochemical stability in aqueous electrolytes with enhanced photocatalytic activities. The titanyl phosphate contributed to the production and stabilization of hydroxyl radicals on the surface of photocatalyst, which facilitated the efficient photooxidation of the organic pollutants. Further, enhancing the photocatalytic hydrogen production was achieved by the titanyl phosphate modified TiO 2 (TP-TiO 2 ). Consequently, the conformal titanyl phosphate passivation enhanced photocatalytic activity of TiO 2 . Comparing to the bare TiO 2 nanoparticles, approximately two-fold higher photocatalytic H 2 production rate was achieved by the TP-TiO 2 .

A review on passivation engineering for improving photocatalytic hydrogen evolution performance

“…The interaction between This journal is © The Royal Society of Chemistry 2024 semiconductors or on the surface of photocatalysts caused by a passivation layer, impurity ions or chemical bonding will alter the bonding energies or result in the formation of a new XPS signal, which provides convincing evidence for revealing changes in the interaction between objects caused by passivation engineering. 61,62,[65][66][67]81 Different from EPR, XPS can be widely applied for all types of inorganic and organic materials, as well as metals and semiconductors. The binding energy of different elements is closely related to the electron cloud density, thus reecting the local change in chemical state and the interaction between different materials.…”

“…Besides the thickness, the materials utilized in the passivation layer is another crucial factor affecting the efficiency of passivation engineering. Although the aim of passivation is to reduce the adverse factors that affect the transfer and utilization of charge carriers, as well as the stability of catalysts, and unavoidable fact is that many passivation materials, including the abovementioned TiO 2 , ZnS, ZnO, and GO, 55, [65][66][67][68][69]78,82,96,97 have special electrochemical properties and inherent catalytic properties. Consequently, the passivation layer should not been seen as a totally chemical inert component, and its basic properties, such as light absorption property, charge transfer ability, and inherent electrochemical properties should also be considered in the design and selection of passivation layer-modied systems.…”

Electronic structures and optoelectronic properties of ATiOPO4 (A = H, Li, Na, K, Rb, Cs, Fr, NH4, Ag) compounds and their applications in water splitting, CO2 reduction, and photo-degradation

“…The enhancement of photocatalytic activity of titanate was induced by doping with phosphorus, and was attributed to the decrease in the recombination of electrons and holes, the narrowed band gap, and thermal stability [25]. The phosphate anion species bound to the titanate surface has promoted the photodegradation of organic pollutants and hydrogen production [26]. The fact that the phosphate species enhanced the photocatalytic reactions motivated us to investigate KTP family.…”