Probing Hydrogen Evolution on Pulsed Laser-Crafted Pt-Infused Oxygen-Deficient Black TiO<sub>2</sub> in Real-Time Using Raman Spectroscopy

Abstract

Oxygen vacancy (O-V)-enriched black TiO2 (BTO) is a promising material for supporting well-studied noble metals in the hydrogen evolution reaction (HER). Blackening TiO2 by incorporating O(V)s substantially changes the electronic state of BTO and enhances HER catalytic performance compared to pristine TiO2. Furthermore, the incorporation of vacancies leads to deviation from a single anatase phase on a localized scale and creates a heterojunction by promoting the occurrence of localized rutile segments. Hence, synthesizing biphasic (rutile and anatase) BTO with abundant O(V)s and optimized Pt-metallic clusters substantially improves the electrochemical HER kinetics, though it demands a complicated multistep synthesis. Conversely, herein, a solvent-free, single-pot green synthesis route is corroborated using a pulse laser irradiation technique to achieve the desired O-v-enriched BTO structure. Controlled irradiation of anatase TiO2 with a Pt precursor under optimized parameters in an air environment creates O(V)s and decorates the metal oxide with Pt nanoclusters. This defect formation decreases the activation energy of BTO, favoring the anatase phase and forming a localized rutile phase, which enhances HER activity through localized heterojunctions. The combined impacts of Pt nanoclusters and O(V)s revealed an outstanding specimen achieving a HER overpotential of 169 mV at 10 mA/cm(2) and a Tafel slope of 73.3 mV/dec Importantly, long-term stability during overall water splitting was further achieved. This approach offers valuable perceptions into designing highly competent catalysts and their supporting structures for various energy-associated solicitations.