Direct solar to hydrogen conversion enabled by silicon photocathodes with carrier selective passivated contacts. Issue 2 (9th December 2021)

• Record Type: Journal Article
• Authors: Sharma, Astha; Duong, The; Liu, Peng; Soo, Joshua Zheyan; Yan, Di; Zhang, Doudou; Riaz, Asim; Samundsett, Christian; Shen, Heping; Yang, Cheng; Karuturi, Siva Krishna; Catchpole, Kylie; Beck, Fiona J.
• Is Part Of: Sustainable energy & fuels. Volume 6:Issue 2(2022)
• Page Start: 349
• Page End: 360
• Publication Date: 2021-12-09
• Subjects: Renewable energy sources -- Periodicals; Fuel cells -- Periodicals; Electric batteries -- Periodicals; Electrochemistry -- Periodicals; 660.297
• DOI: 10.1039/d1se01260f
• Languages: English
• ISSNs: 2398-4902

Abstract

Abstract : Si photocathode with industrially relevant charge selective passivation and physically deposited earth-abundant catalyst is developed with an efficiency above 10%. Solar-to-hydrogen efficiency of 17% is achieved by combining perovskite PV in tandem. Abstract : Direct solar hydrogen generation using systems based on low-cost materials is a potential pathway to achieve low-cost renewable hydrogen at large scale, and photoelectrodes that leverage well-established silicon (Si) technology are a particularly promising approach. Two key requirements to achieve highly efficient and stable Si photoelectrodes are electronic passivation to reduce recombination losses at the Si/catalyst interface, and chemical protection of Si from corrosion in the alkaline electrolyte. In this work, Si photocathodes are fabricated by employing a carrier selective passivation layer consisting of an ultrathin SiO x (∼1.4 nm) capped with n + polycrystalline Si (∼70 nm), and a compact NiMo/Ni bilayer catalyst. The Si photocathodes integrated with Earth abundant catalyst and state-of-art charge selective passivation layer achieve an applied bias to photon conversion efficiency of 10.5%, and high stability above 60 hours. Importantly, the NiMo/Ni catalyst is developed using the industry-relevant sputter deposition method presenting vertically aligned, rod-like nanostructures with a low overpotential of 89 mV at 10 mA cm −2 for the hydrogen evolution reaction (HER). Finally, a remarkable overall unassisted water splitting efficiency of 17% is achieved for an all-low-cost materials-based system, by combining the Si photocathode with a high bandgap perovskite PV top cell in tandem configuration, and a high-performance NiFe electrode for oxygen evolution reaction.