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The unrestrained charge recombination inherently associated with inorganic semiconductors renders them inefficient for the targeted photocatalytic applications in their pristine state. A variety of compositing strategies have thus become important to mitigate the charge recombinations in this regard. In the present work, we report a modified solvothermal synthesis route to affect the synthesis of appropriately band-aligned h-BN/Sb 2 WO 6 nano-composite. The later offers improved photocatalytic efficiency owing to reduced electron-hole recombination ensured through the intimate interfacial contact ascribed to the modified synthesis strategy. The most efficient of h-BN and Sb 2 WO 6 compositions (12-wt % h-BN/Sb 2 WO 6) depicted an 80.8 % photo-catalytic degradation of Rhodamine B (RhB) in 90 min under visible light irradiation compared to 42 % for pure Sb 2 WO 6. The photocatalytic degradation of RhB exhibits k app value of 1.73 × 10 À 2 min À 1 which is 2.8 times greater than k app values of pristine Sb 2 WO 6 (6.01 × 10 À 3 min À 1). The radical scavenger tests reveal that the superoxide radicals (* O 2 À 1) and holes (h +) are the main reactive species. Additionally, composite catalyst revealed a commendable photostability with 77.29 % retention of photocatalytic efficiency after four catalytic cycles.

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Oxide-based systems often suffer from higher overpotentials compared to transition metal sulfides and phosphides for the electrochemical hydrogen evolution reaction (HER). Interestingly, the generation of oxygen vacancy/defect has been seen as the strategy for further activating transition metal oxides (NiCo 2 O 4 as a model system) for an electrochemical watersplitting process. Herein, we employ the temperature ramp strategy (ambient air calcination) for the generation of oxygen vacancies in NiCo 2 O 4 (NCO) towards the tuning of electrocatalytic enhancements. The NiCo 2 O 4 synthesized at temperature ramp rates of 2 °C/min (NCO-2), 5 °C/min (NCO-5), and 10 °C/ min (NCO-10) depicts contrasting structural features and varying Ni : Co : O surface composition. The decrease in the crystallite size and converse trend in the particle strain were observed from NCO-2 to NCO-10. Interestingly, the surface Ni : Co : O ratios of 1 : 0.78 : 3.6, 1 : 0.81 : 3.3, and 1 : 0.69 : 2.8 for NCO-2, NCO-5, and NCO-10, respectively, were observed. The reduced relative oxygen ratio in the latter implies the generation of an ample amount of oxygen vacancy defects. HER performance depicts a consistent trend with enhanced oxygen defect concentration with the overpotential requirement of 700, 647, and 597 mV for NCO-2, NCO-5, and NCO-10, respectively, for the generation of a cathodic current of 25 mA cm À 2 . The same trend in an electrocatalytic enhancement is observed for other cathodic currents.

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