P25-induced polydopamine conformal assembly on Cu2O polyhedra for hydrophilic and stable photoelectrochemical performance

Abstract

Cu₂O has begun to show its charm and gain popularity in various photoelectrochemical (PEC) processes, but fast charge recombination and photochemical instability always limit its PEC water splitting activity and stability. Furthermore, H₂O wetting on the Cu₂O photocathode is the premise for PEC reaction, while research on carrier separation, photostability and still wettability has not been brought to the forefront. Herein, a self-polymerized dopamine coating is employed to directly anchor TiO₂ (P25) on the surface of a Cu₂O film electrode; nanoscale particles facilitate polydopamine (PDA) conformal assembly on Cu₂O polyhedra. A ternary Cu₂O/PDA/TiO₂ composite photocathode is obtained and shows boosted PEC activity and stability. The advantages of this unique design are mainly reflected in three aspects: (1) the married heterojunction of TiO₂/Cu₂O provides a persistent driving force for charge separation by PDA natural adhesive properties; (2) the conversion of hydrophobicity–hydrophilicity is achieved to improve the wettability of the Cu₂O film electrode assisted by conformal PDA coating; (3) the improvement of PEC stability is due to the inhibition of Cu₂O photocorrosion covered by the PDA shelter. This advance bodes well for the development of the PEC field founded on multifunctional PDA.