Controlling the oxidation and chemistry of photodeposited CuOX species via charge density modulation

Abstract

Controlling the oxidation state and chemical environment of photodeposited metal species remains a fundamental challenge in photocatalysis, as these are dictated by complex and poorly understood metal–support interactions. Here, we suggest a general mechanism by which doping of a photocatalyst substrate (anatase {0 0 1} facets) modulates the local chemical potential and oxygen activation pathways, thereby directing the oxidation, coordination and reactivity of photodeposited CuOX clusters. Using shallow donor (Nb⁵⁺) and acceptor (Ga³⁺) species as model systems, a combined DFT, spectroscopy and reactivity analysis reveals that Nb-induced electron-rich environment promote O₂ adsorption and O–O dissociation at NbTi-Cu interfacial sites, accelerating Cu⁺/Cu²⁺ cycling, while Ga-induced electron withdrawal suppresses O₂ dissociation and stabilizes hydrogen peroxide. Further validation confirmed similar effects for Sc3+ and Al3+ as alternative acceptors. As a proof-of-concept we used the 2% Nb-doped material with deposited 0.5% Cu for achieving state-of-the-art 400 nmol∙min 1 rate of the hydroxyl radicals generation (probed by coumarin in neutral pH) with 0.5 mM PMS assistance. Finally, we presented high quantum efficiencies/relative photonic efficiencies of this material in degradation of selected pollutants: phenol (20/299%), naphthalene (56/706%), EE2 (18/170%) and methomyl (100/1043%).