Plasmonic Au Grid–CdSe Heteropatterned Film by Topochemistry and CdCl₂ Surface Passivation for Photoelectrochemical Hydrogen Evolution

Constructing patterned film photoanodes with economizing raw chemicals but enhancing photoelectrochemical (PEC) performance is attractive for practical applications. However, simultaneously optimizing light scattering and interfacial charge transfer through plasmonic enhancement remains challenging. Herein, we developed a novel plasmonic photoanode featuring Au grids and a nanometer-thick CdSe layer (Au grid-CdSe) with well-organized heterointerfaces, fabricated via a facile colloidal topochemical strategy. This design leverages the synergistic coupling between plasmons and excitons in plasmonic heteropatterned films. The underlying patterned Au grids serve dual functions: as an electron collector and light reflector. Their highly ordered Bragg structure effectively scatters incident light into the ultrathin CdSe layer. Furthermore, CdCl₂ surface passivation of the Au(grid)-CdSe heteropatterned photoanode, based on this unique light absorption/reflector architecture, yielded a photocurrent density of 4.51 mA cm^-2, representing significant enhancement. Compared to similarly prepared Au-CdSe heterofilms, the passivated Au(grid)-CdSe heteropatterned films exhibited 2.0-fold higher PEC hydrogen evolution performance, maintained excellent stability for over 26 h, and reduced Au consumption by 32%. This strategy offers a novel pathway for improving the performance of semiconductor-based optoelectronic devices.