Photoelectrochemical (PEC) water-slit solar cells have been considered as a feasible and cost-effective realization of an artificial analogue of photosynthesis. Unfortunately, stringent physical and chemical property requirements complicate the search for suitable photoelectrodes that can efficiently perform solar energy conversion. Innovations in nanoarchitectured photoelectrodes offer potential breakthroughs in this field. Using various template fabrication techniques, photoelectrodes with different nanoarchitectures have been obtained and applied to solar water splitting, e.g., a quaternary macromesoporous 3D architecture that shows excellent solar energy conversion efficiency (ACS Nano 2014, 8, 7088); TiO2 / Al-doped ZnO nanotip arrays as a 3D current collector of PEC devices to improve light harvesting in both UV and visible regions (Adv. Energy Mater. 2016, 6, 1501496); and nanoparticle superlattices with programmable multiple plasmonic resonances to improve photoelectrochemical activity (Adv. Funct. Mater. 2020, 30, 2005170).
Replicated from AAO templates, various highly ordered metallic nanopore arrays were rationally designed and fabricated and well studied for energy conversion applications. Cobalt nanopore arrays combined with well-dispersed platinum nanoparticles showed significantly enhanced catalytic activities as an electrode for hydrogen evolution reaction (Appl. Catal. B: Environ. 2019, 244, 87). Self-aligned two-pore nickel nanopore arrays at wafer scale with broadband solar absorption properties enable highly efficient solar energy harvesting (Nano Energy 2019, 58, 543).