Development of BiVO4-based hyperfine heterojunctions for photoelectrochemical reactions

• Grant number: 23/15633-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2024
• End date: August 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Renato Vitalino Gonçalves
• Grantee: Niqab Khan
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 23/00618-6 - Development of Semiconductor Devices for Green Hydrogen Production via Photoelectrochemical Water Splitting without External Polarization, AP.PFPMCG.R

Abstract

The postdoctoral fellowship activity plan proposes the study of the deposition of bismuth vanadate (BiVO4) films on a conductive glass substrate, and the formation of hyperfine heterojunctions to increase chemical stability in an aqueous medium and accelerate charge transfer on the surface. BiVO4 (BVO) material is an n-type semiconductor with very promising structural and electronic characteristics for oxygen evolution reactions (OER), such as narrow bandgap energy (~2.4 eV), high absorption coefficient, stability chemical potentials in solutions with a wide pH range. However, BiVO4 under illumination in a solution with a pH close to neutral, can become unstable, due to the near Fermi level of holes undergoing changes to more anodic potentials, and redefining the chemical stability of the material. In this project, we will study the formation of BiVO4 photoanodes with high thickness control and we will investigate stability over a wide range of pH potential, with different buffered electrolytes (borate, phosphate and citrate). A detailed study will be carried out on the formation of hyperfine heterojunctions (< 3nm) with protective layers for the reaction and oxygen evolution (OER). Finally, after obtaining a stable system with high activity for OER, we will use BiOV4 as a photoanode on one side of the tandem cell, which will be applied to the hydrogen generation system without external potential (bias-free). In addition to studying the formation of a stable photoanode, the PD scholarship candidate will study the electronic properties of materials to construct the energy band diagram, using advanced surface techniques, such as XPS, UPS and Mott-Schottky.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

KHAN, NIQAB; KOCHE, ARIADNE; KHAN, WAHIDULLAH; NOGUEIRA, PALLAS A. M.; JAMIL, ASIF; PIEPER, YVONNE; TOMA, FRANCESCA M.; NASCIMENTO, OTACIRO R.; GONCALVES, RENATO V.; KHAN, SHERDIL. Optimizing photocatalytic water oxidation by FeMnO_x bimetallic cocatalyst on Zn-doped BiVO₄ via magnetron sputter deposition. APPLIED CATALYSIS A-GENERAL, v. 704, p. 10-pg., 2025-08-25. (23/15633-0, 14/50279-4, 20/15230-5, 23/00618-6)