Self-oriented Sb₂Se₃ nanoneedle photocathodes for water splitting obtained by a simple spin-coating method

Synthesis of one-dimensional nanostructured chalcogenide compounds using nontoxic and abundant constituents provides an important pathway to the development of commercially feasible photoelectrochemical water splitting. In this study, grass-like Sb₂Se₃ nanoneedle arrays are successfully fabricated on a substrate via a facile spin-coating method without any complicated processes such as templating, seed formation, or use of a vapor phase. Preferential [001] growth of the initial single-crystalline Sb₂Se₃ occurs during the first spin-coating, but interfacial defects are generated upon subsequent spin-coating iterations, resulting in annual-ring-like growth of Sb₂Se₃ nanoneedles. After sequential surface modification with TiO₂ and Pt, the resistance to charge transfer from the photoelectrode to the electrolyte decreases significantly, yielding a remarkable record-high photocurrent of 2 mA cm^-2 at 0 V_RHE (4.5 mA cm^-2 at -0.2 V_RHE).