Towards Environment Friendly Hydrothermally Synthesized Li + , Rb + , In 3+ Intercalated Phosphotungstate (PW 12 O 40 ) Thin Films.

In the present investigation, a one-step hydrothermal approach is proposed to synthesize Li + , Rb + , and In 3+ intercalated PW 12 O 40 (PTA) thin films. The photoelectrochemical performance of the deposited Li 3 PW 12 O 40 (Li-PTA), Rb 3 PW 12 O 40 (Rb-PTA), and In 3 PW 12 O 40 (In-PTA) photocathodes were investigated using a two-electrode cell configuration of FTO/Li 3 PW 12 O 40 /(0.1 M I - /I 3- ) aq. /Graphite. The energy band gaps of 2.24, 2.11, and 2.13 eV were observed for the Li-PTA, Rb-PTA, and In-PTA films, respectively, as a function of Li + , Rb + , and In 3+ . The evolution of the spinal cubic crystal structure with increased crystallite size was observed for Rb + intercalation within the PTA Keggin structure, which was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed a modification in the surface morphology from a rod-like structure to a densely packed, uniform, and interconnected microsphere to small and large-sized microspheres for Li-PTA, Rb-PTA, and In-PTA, respectively. Compositional studies confirmed that the composing elements of Li, Rb, In, P, W, and O ions are well in accordance with their arrangement for Li + , Rb + , In 3+ , P 5+ , W 6+ , and O 2- valence states. Furthermore, the J-V performance of the deposited photocathode shows power conversion efficiencies (PCE) of 1.25%, 3.03%, and 1.62%, as a function of the incorporation of Li + , Rb + , and In 3+ ions. This work offers a one-step hydrothermal approach that is a prominent way to develop Li + , Rb + , and In 3+ ions intercalated PTA, i.e., Li 3 PW 12 O 40, Rb 3 PW 12 O 40 , and In 3 PW 12 O 40 photocathodes for competent solar energy harvesting.