Substrate-induced assembly of PtAu alloy nanostructures at choline functionalized monolayer interface for nitrite sensing

•An efficient electrochemical method was developed for the construction of alloy nanoclusters.•The formation of alloy nanoclusters was induced by choline functionalized monolayer substrate.•Choline film could provide a suitable local microenvironment with –N+(CH3)3 polar head groups.•Choline film was favorable for the progressive nucleation of alloy nanocrystals and the mass transfer of precursors.•The alloy nanoclusters exhibited remarkable electrocatalytic activity towards the oxidation of nitrite.

PtAu alloy nanostructures (nanoclusters) with desired surface structure and properties were constructed at choline functionalized monolayer interface. The significance of choline substrate was to provide a suitable local microenvironment with –N+(CH3)3 polar head groups, which was favorable for the progressive nucleation of alloy nanocrystals, as well as the mass transfer of AuCl4− and PtCl62−. The formation process and mechanism of the nanoclusters were investigated, and the physicochemical properties of the nanoclusters were characterized. Electrochemical experimental results demonstrated that the as-prepared nanoclusters exhibited remarkable electrocatalytic activity towards the oxidation of nitrite due to the ensemble effect and ligand effect of alloy material. Based on the catalytic performance of alloy nanoclusters, the electrode reaction kinetics of nitrite oxidation was studied. Moreover, the analysis of nitrite was realized in real samples including pond water, industrial wastewater, and milk samples, suggesting that the system is beneficial for environmental monitoring and food safety assessment.