Fabrication of porous 1D WO3 NRs and WO3/BiVO4 hetero junction photoanode for efficient photoelectrochemical water splitting

Abstract

Porous columnar nanostructured photoelectrodes may significantly affect the photoelectrochemical (PEC) water splitting efficiency. The glancing angle deposition (GLAD) technique is the most popular method to fabricate columnar nanostructured thin films. Here, we have fabricated vertically aligned porous 1D tungsten oxide nano-rod (1D WO3 NRs) thin films by DC magnetron sputtering method using glancing angle deposition with a constant rotation speed of 5 rpm. The depositions carried out at various deposition angles of α = 0°, 60°, 70°, 75°, 80°, and 85°. The deposited 1D WO3 NRs adopted a monoclinic structure oriented in the (002) crystalline plane perpendicular to the FTO substrate. Using systematic deposition conditions, the porous columnar 1D WO3 NRs were engineered to find the effect on the photoelectrochemical water splitting. Photocurrent density of the 1D WO3 NRs photoanodes was tested in near-neutral pH (0.5 M Na2SO4) electrolyte solutions. Under the optimum conditions, the 1D WO3NRs photoanode led to the premier photocurrent density of 1.04 mA/cm2 (1 V vs. Ag/AgCl) due to the optimum surface porosity in the 1D WO3 NRs. The individual layer of BiVO4 photoanode exhibited a photocurrent density of 1.24 mA/cm2 (1V vs. Ag/AgCl). Highest photocurrent density of 2.24 mA/cm2 with high photo-stability was observed in optimized heterostructure of 1D WO3 NRs/BiVO4 photoanode.