Photoelectrochemical detection of calcium ions based on hematite nanorod sensor substrates

α-Fe2O3 (hematite) thin films have been shown to be a robust sensor substrate for photoelectrochemical imaging with good stability and high spatial resolution. Herein, one-dimensional (1D) hematite nanorods (NRs) synthesized via a simple hydrothermal method are proposed as a substrate, which provides nanostructured surfaces with enhanced photocurrent responses, good stability and excellent spatial resolution for potential imaging applications. The photoelectrochemical sensing capability of hematite NRs was demonstrated by a high pH sensitivity without modification and by an amperometric response to calcium ions (Ca2+) when modified with a thin ion-sensitive membrane.