The preparation of a AuCN/prussian blue nanocube composite through galvanic replacement enhances stability for electrocatalysis

A stable AuCN/Prussian Blue (PB) Nanocube composite was prepared by galvanic replacement of PB cubes with HAuCl4 solution. The simple one-step method leads to a composite with an increased surface area and pore volume, but smaller surface pore sizes than pure PB cubes. When the electrochemical detection of H2O2 was used as a model electrocatalytic reaction, the AuCN/PB composite showed considerably improved stability. This stability is evident in a stable current response, lower background current, and improvement in both sensitivity and limit of detection compared to pure PB. This stability was attributed to the stabilisation of the surface of PB with AuCN, which prevents decomposition of the reduced form of PB during electrocatalysis. The new material shows that redox active Metal Organic Frameworks (MOFs) used for electrochemical sensing or catalysis can be tuned for surface porosity, and stabilised via galvanic replacement with a noble metal salt, leading to improved electroanalytical performance.