Fabrication of sandwich structured C/NiO/TiO2 nanotube arrays for enhanced electrocatalytic activity towards hydrogen evolution

A sandwich structured C/NiO/TiO2 nanotube arrays (C/NiO/TiO2 NTAs) were presented for highly efficient water splitting. The NiO nanoparticles were deposited on the inner wall of anodized TiO2 NTAs, followed by coating a carbon nanofilm via carbonization of a polydopamine membrane. The C/NiO/TiO2 NTAs exhibit a superior HER activity to most earth-abundant electrocatalysts, with an overpotential of 86 mV at 10 mA cm−2, a Tafel slope value of 67.1 mV dec−1 and almost no degradation of HER activity after successive operation for 24 h.