Efficient Photoelectrochemical Hydrogen Production Utilizing Advanced Integrated Heterostructures Silicon Solar Cells and 2D-Material

Abstract

Abstract To avoid air pollution and global warming correlated with utilize utilizing fossil fuels to produce hydrogen. Developing new renewable technologies for generating H2, such as photoelectrochemical water splitting, is undoubtedly important for the future of this clean energy carrier. In fact, most of the H2 today is produced from the steam-reforming methane, which produces environmentally, and health hazard gases, such as CO2. To address this critical challenge, researchers tend to generate H2 by utilizing a promising alternative method to the current CO2-emitting fossil fuel, such as electrolysis of water. A Photoelectrochemical (PEC) unit consists of three essential components: a light absorber that generates electron-hole pairs upon illumination and a co-catalyst combined as a photocathode. This photocathode's structure facilitates charge transfer and reduces the resultant overpotential for gas production. In addition to the reference electrode (made of metal such as Pt) and electrolyte (acid-based solution). The Si-heterojunction solar cell (Si-HJ) is applied as a photocathode due to its high open-circuit voltages (VOC), high-circuit current density (JSC), and excellent photon management to avoid recombination by the surface structuring. Moreover, the Si-HJ cell has high efficiency due to its periodic micro-pyramid (MP) structure, which has the omnidirectional broadband ability to trap light. Moreover, co-catalyst materials possess characteristics such as a chemical match between Si-HSC/co-catalyst and high stability during the operation. In addition, an earth-abundant, inexpensive, non-toxic, and highly efficient catalytic characteristic toward H2 generating can be integrated into photocathodes. Several characterization methods were utilized to investigate the performance of developed Si-HSC/co-catalyst based PEC. We demonstrate Si-HSC/co-catalyst as an efficient photocathode for PEC H2 production. The Si-HSC/co-catalyst photocathode shows an ability to address the shortcoming of each component. We have achieved a half cell solar-to-hydrogen (STH) conversion efficiency of 5.57% under AM 1.5G illumination with a maximum photocurrent density of 36.33 mA/cm2 and an onset potential of 0.5 V vs. RHE. Besides, the electrochemical impedance spectroscopy (EIS) elucidates that the integration of co-catalyst significantly reduced the charge transfer resistance and thereby enhanced the PEC H2 production performance of Si-HSC/co-catalyst based PEC. Accordingly, the integration of Si (excellent light harvesting) and co-catalyst (H2 catalytic ability, and chemical protection) results in fabricating of an earth-abundant catalyst coupled photocathode that has an efficient and stable PEC H2 production characteristics.