Development of Semiconductor Devices for Green Hydrogen Production via Photoelectrochemical Water Splitting without External Polarization

• Grant number: 23/00618-6
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• Duration: September 01, 2023 - August 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Renato Vitalino Gonçalves
• Grantee: Renato Vitalino Gonçalves
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated researchers: Frank Erich Osterloh ; Jesum Alves Fernandes ; Washington Santa Rosa ; Yara Jaqueline Kerber Araujo
• Associated scholarship(s): 23/15633-0 - Development of BiVO4-based hyperfine heterojunctions for photoelectrochemical reactions, BP.PD

Abstract

Green hydrogen (H2V) has been proposed as a clean alternative to replace fossil fuels in the transport and electricity generation sector, since its use in a fuel cell only produces water vapor as a by-product. Hydrogen has the highest energy-to-weight ratio compared to fossil fuels, where in 1 kg of H2 it is possible to convert up to 30 kWh of useful energy, while with gasoline it is possible to obtain 10 kWh/kg. Green hydrogen is that produced from clean and renewable energy sources, being considered the best candidate for the "Race to Zero" campaign, which is a global agenda, with goals to zero net emissions of greenhouse gases by 2050. Artificial photosynthesis is one of the most promising processes for generating green hydrogen, since H2 is produced by water splitting using a semiconductor material and sunlight. However, intrinsic problems of semiconductor materials, such as high charge recombination, instability and low electronic diffusion are some of the factors responsible for the poor performance of current devices in artificial photosynthesis. In this project, we will focus our efforts on the development of a two-electrode device; n-type semiconductor and p-type semiconductors, based on n-BiVO4, p-CuO and p-Cu2O materials, respectively. Specifically, we will study the doping of the n-BiVO4 structure, associated with the formation of heterojunctions with FeMOx semiconductor ferrites (M = Ni, Mn), which have great potential to improve the transport and charge separation properties, resulting in a reduction in the rate recombination of the electron-hole pair. CuO and Cu2O p-type semiconductors are abundant and low-cost materials that have high theoretical photocurrent densities of 7.5 mA/cm2 for BiVO4, 35 mA cm-2 for CuO and ~15 mAcm-2 for Cu2O. However, despite having a band gap in the range of 1.2 - 2.0eV, they have defects in the electronic structure, which limit the transfer of charges, associated with redox potentials that have energy between the conduction and valence bands, which inevitably leads to the occurrence of auto-photoreduction or auto-oxidation after lighting, which results in low chemical stability, is a barrier to be overcome. In this project we will increase the efficiency of charge transport to the surface, and overcome the instability of p-type semiconductors through the deposition of hyperfine layers (< 3 nm) and doping of the electronic structure. The final device will have a configuration of two electrodes of optimized materials based on n-BiVO4 and p-CuO/Cu2O with high absorption of sunlight in the visible spectrum region, which will provide the production of H2V via artificial photosynthesis without external polarization (zero bias). (AU)