An atomically thick titanium phosphate thin layer with enhancing electrochemical sensitivity toward Pb(II)

Here we show for the first time the stripping signals for sensitivity identification of Pb(ii) using a titanium phosphate (TiP) thin layer. An atomically thick TiP thin layer with 0.70 nm has been successfully exfoliated from the bulk α-TiP. A sensing interface for ultra-sensitive detection of Pb(ii) by using the TiP thin layer as an electrode coating has been demonstrated for ultra-sensitive and selective electrochemical sensing toward heavy metal ions (e.g., Pb(ii)). A range of Pb(ii) contents in micro-moles (0.05 to 0.6 μM) at the TiP thin layer with a sensitivity of 23.60 μA μM^-1 and a limit of detection of 0.91 nM have been investigated. Determining the responses of Zn(ii), Cd(ii), Cu(ii) and Hg(ii) as the most appropriate choice for comparison, the stripping voltammetric quantification of Pb(ii) with high sensitivity and selectivity at the thin layer has been proved. As compared with bulk α-TiP, the TiP thin layer exhibited better detection performance toward Pb(ii) which could be ascribed to the atomic thickness and higher adsorption capacity. Furthermore, XPS was applied to characterize the sorption behavior of Pb(ii) on the surface of the TiP thin layer. Importantly, this work has a wider significance in that the system of an atomically thin layer offers possibilities to improve the sensitivity of the electrochemical analysis for Pb(ii).