Ultrathin Al2O3 passivation layer-wrapped Ag@TiO2 nanorods by atomic layer deposition for enhanced photoelectrochemical performance

Abstract In this study, new one-dimensional (1D) titanium dioxide nanorod (TONR) array films sensitized with Ag nanoparticles (ANPs) and coated with ultrathin alumina (Al2O3) passivation layer were synthesized. ANPs and Al2O3 passivation layer were deposited via magnetron sputtering technology and atomic layer deposition (ALD) method, respectively. The morphology, structure, composition, optical properties, and PEC properties on varied amounts ANPs and tailored Al2O3-modulated TONR films were investigated systematically. The results exhibited that with an optimal thickness of the Al2O3 layer and a suitable sputtering time of ANPs, the TONR arrays can effectively restrain the recombination of electron-holes and improve the PEC performance. Furthermore, 20 cycles of Al2O3 passivation on Ag10@TONR shows the optimal PEC performance with the maximum photocurrent density (~0.34 mA/cm2), which is almost 5 times higher than that of Ag10@TONR (~56.9 μA/cm2) and 30 times as much as that of pure TONR (~11.3 μA/cm2). The superior PEC performance of Al2O3-Ag@TONR is ascribed to the local surface plasmon resonance (LSPR) effect of ANPs, and the passivation effect of the Al2O3 coating layer.