Nanoscale Engineering of Si/BDD/TiO2 heterostructure interfaces to enhance photoelectrochemical performance

The photocatalytic efficiency of BDD/TiO₂ photoelectrodes is enhanced by increased electrical fields due to nanostructuring of their interfaces. The interfaces of Si/BDD/TiO₂ heterostructure electrodes were engineered at the nanoscale, combining microstructuring of the Si substrate with nanostructuring of the boron-doped diamond (BDD) film. The hierarchical design increased the generated photocurrent by 6.5 times compared to ITO/TiO₂ electrodes and 4.6 times compared to unstructured BDD/TiO₂ electrodes. Both micro- and nanostructuring also lowered the threshold potential for photocurrent onset by 0.2 V, and nanostructuring also delayed photocurrent decay at higher applied potentials. The enhancement is related to a novel finding concerning the electrical field enhancement effect at the tip-like structured interfaces, which greatly improves the charge transfer through the heterostructure. In addition, the structured electrodes showed significant improvements in stability and resistance to delamination, making them highly competitive with state-of-the-art BDD/TiO₂ photoelectrodes for water treatment and hydrogen production applications.