Dual-bonding interactions between MnO2 cocatalyst and TiO2 photoanodes for efficient solar water splitting

MnO2 cocatalyst anchored with Mn-O/N bonds on TiO2 nanotube arrays could efficiently promote the holes transfer and photoelectrochemical water splitting. [Display omitted] •Surface oxygen vacancies and N-doping of TiO2NTs could facilitate the growth of MnO2 cocatalyst with Ti-O/N-Mn dual-bonds.•Dual-bonding interactions between TiO2 and MnO2 interfaces could efficiently promote the holes transfer and water oxidation.•A remarkably improved photocurrent density for MnO2/N-TiO2 has been achieved, 3.4 times higher than that of pure TiO2 NTs. Severe charge recombination and sluggish water oxidation kinetics greatly limited the practical applications of photoelectrochemical (PEC) water splitting. Herein, we demonstrated the nitrogen plasma treatment for simultaneously achieving oxygen vacancies and N-doping on TiO2 nanotube arrays. More importantly, the oxygen vacancies and N-doping could effectively promote the selective construction of MnO2 cocatalyst anchored with Mn-O/N bonds on TiO2 nanotube arrays, which could efficiently narrow charge depletion layer and promote the holes transfer from TiO2 to MnO2. As expected, this photoanode achieves a remarkably increased PEC performance (1.95 mA cm−2 at 1.23 VRHE), up to 3.4 times higher than that of pristine TiO2 (0.57 mA cm−2 at 1.23 VRHE), and excellent stability for water splitting. These demonstrations may provide a new insight for designing highly efficient TiO2-based photoanodes for solar energy conversion.