Synthesis of Ag/Cu decorated 3D self-assembled nanowire TiO2 photocatalyst for hydrogen production: a promising pathway towards sustainable energy generation.

ABSTRACT

Here, synthesis and characterization of TiO2 with different morphologies along with the cost-effective bimetallic decoration on optimized 3D self-assembled nanowire TiO2 (NWT) photocatalyst (Ag/Cu-NWT) with overwhelming hydrogen production rate is reported. All the photocatalysts were well characterized by different characterization techniques. Initially, the effect of morphology change obtained by changing the NaOH concentration has been studied for TiO2. Morphology obtained at 10 M NaOH solution, i.e., NWT (678 µmol/g), showed better hydrogen production than morphology obtained at 5 M (410 µmol/g), 15 M (210 µmol/g), and 20 M (160 µmol/g) NaOH solutions. Further, with the aim to achieve comparable or better activity low-cost photocatalyst as compared to Pt-TiO2 system, NWT was decorated with various Cu percentages and then with a minimal percentage of Ag on an optimized Cu-NWT photocatalyst. The observed trend for photocatalytic hydrogen production has been found to be P25 TiO2 < NWT < 1.0Cu-NWT < 0.5Pt-NWT ≤ 0.1Ag/1.0Cu-NWT. The marked increase by a factor of 103 in hydrogen production for the optimized bimetallic 0.1Ag/1.0Cu-NWT (10,184 µmol/g) photocatalyst compared to P25 TiO2 (99 µmol/g), nearly threefold increment in hydrogen production than an optimized 1.0 Cu-NWT (3907 µmol/g) photocatalyst and comparable hydrogen production as compared to 0.5Pt-NWT (10,050 µmol/g) may be attributed to the successful synthesis of a highly porous NWT morphology, which offers large surface area, increased light absorption combined with the synergistic effects of surface plasmon resonance (SPR), and the Schottky barrier for H+ reduction to H2 gas. The optimization of TiO2 morphology and an inexpensive bimetallic decoration strategy opens up promising opportunities for the development of cost-effective photocatalysts in the realm of energy and environment.