Pseudomorphic Transformation of Interpenetrated Prussian Blue Analogs into Defective Nickel Iron Selenides for Enhanced Electrochemical and Photo-Electrochemical Water Splitting

A significant methodology gap remains in the construction of advanced electrocatalysts, which has collaborative defective functionalities and structural coherence that maximizes electrochemical redox activity, electrical conductivity, and mass transport characteristics. Here, a coordinative self-templated pseudomorphic transformation of an interpenetrated metal organic compound network is conceptualized into a defect-rich porous framework that delivers highly reactive and durable photo(electro)chemical energy conversion functionalities. The coordinative-template approach enables previously inaccessible synthesis routes to rationally accomplish an interconnected porous conductive network at the microscopic level, while exposing copious unsaturated reactive sites at the atomic level without electronic or structural integrity trade-offs. Consequently, porous framework, interconnected motifs, and engineered defects endow remarkable electrocatalytic hydrogen evolution reaction and oxygen evolution reaction activity due to intrinsically improved turnover frequency, electrochemical surface area, and charge transfer. Moreover, when the hybrid is coupled with a silicon photocathode for solar-driven water splitting, it enables photon assisted redox reactions, improved charge separation, and enhanced carrier transport via the built-in heterojunction and additive co-catalyst functionality, leading to a promising photo(electro)chemical hydrogen generation performance. This work signifies a viable and generic approach to prepare other functional interconnected metal organic coordinated compounds, which can be exploited for diverse energy storage, conversion, or environmental applications.