A three-dimensional hexagonal fluorine-doped tin oxide nanocone array: a superior light harvesting electrode for high performance photoelectrochemical water splitting

<div> Photonic nanostructures hold great promise in promoting light harvesting. Here&nbsp;</div> <div> &nbsp;</div> <div> we report the first design and construction of a three-dimensional (3D) hexagonal&nbsp;</div> <div> &nbsp;</div> <div> nanocone array of fluorine-doped tin oxide (FTO) on glass as an excellent electrode&nbsp;</div> <div> &nbsp;</div> <div> for photoelectrochemical (PEC) water splitting. The PEC current density with&nbsp;</div> <div> &nbsp;</div> <div> suitably deposited Ti-doped hematite at 1.23 V vs. the reversible hydrogen electrode&nbsp;</div> <div> &nbsp;</div> <div> (RHE) was increased by 86% to 2.24 +/- 0.02 mA cm(-2) compared to that with the&nbsp;</div> <div> &nbsp;</div> <div> planar counterpart, mainly ascribable to the special light harvesting effect and the&nbsp;</div> <div> &nbsp;</div> <div> electrode surface area provided by 3D FTO. Upon the embedment of a gold layer to&nbsp;</div> <div> &nbsp;</div> <div> concentrate the incident light onto the hematite layer and the deposition of the&nbsp;</div> <div> &nbsp;</div> <div> Co-Pi catalyst with a modified procedure, the photocurrent experienced a large&nbsp;</div> <div> &nbsp;</div> <div> cathodic shift of onset potential by 360 mV and soared to a high value of 3.39 +/-&nbsp;</div> <div> &nbsp;</div> <div> 0.01 mA cm(-2) (at 1.23 V), yielding a power conversion efficiency of 0.70% at a&nbsp;</div> <div> &nbsp;</div> <div> potential as low as 0.88 V vs. RHE.&nbsp;</div