High-Performance Ultrathin BiVO₄ Photoanode on Textured Polydimethylsiloxane Substrates for Solar Water Splitting

Photoelectrochemical (PEC) water splitting devices rely on light-absorbers to absorb sunlight, and the photogenerated electrons and holes further react with water to generate hydrogen and oxygen. Fabricating light-absorbers on textured substrates offers alternative routes for optimizing their PEC performance. Textured substrates would greatly enhance both light absorption and surface reactions of photoanodes and thus reduce the total amount of light-absorbers needed. Herein, we report the fabrication of ultrathin BiVO₄ photoanode film on textured polydimethylsiloxane (PDMS) substrates by using a modified water-assisted transfer printing method. Significantly, a pristine BiVO₄ photoanode of only 80 nm thick shows a photocurrent density of 1.37 mA/cm² at 1.23 V_RHE on patterned PDMS substrates, which is further increased to ∼2.0 mA/cm² at 1.23 V_RHE when FeOOH oxygen evolution catalyst is added. We believe that our transfer printing method can be broadly applied to integrate photoelectrodes and other thin-film optoelectronic devices (e.g., solar cells and electronics) onto diverse textured substrates to enhance their performance.