In-situ nanoarchitectonics of Ni₃FeN/Ni₃Fe heterostructure via facile synthesis of vacancy-rich NiFe PBA for enhanced hydrogen evolution reaction

Hydrogen is eco-friendly with a high energy density, leading to a growing-demand for developing efficient and cost-effective catalysts. For efficient hydrogen evolution reaction (HER), nanoarchitectonics strategy by constructing heterostructure can provide numerous catalytic active sites with enhanced intrinsic activity. This study aimed to achieve enhanced kinetics of HER by in-situ nanoarchitectonics of Ni₃FeN/Ni₃Fe heterostructure. Vacancy-engineered NiFe PBA, the precursor, was synthesized using a facile hydrothermal method via hydrogen peroxide concentration control without complicated or multiple processes. An in-situ Ni₃FeN/Ni₃Fe heterostructure was generated through ammonolysis of vacancy-engineered NiFe PBA. Theoretical interpretation by density functional theory (DFT) calculations confirmed that electron transfer from Ni₃Fe to Ni₃FeN 0.51 e leads to an H adsorption energy down shift (0.36 eV to 0.20 eV), which facilitates catalytic HER. Off-line catalytic alkaline HER performance also showed enhanced kinetic activity with an overpotential of 135 mV at a current density of 10 mA cm⁻². Furthermore, the stability at 200 mA cm⁻² for 100 h showed only 6.61 % decrease in performance, which demonstrated the durability of the Ni₃FeN/Ni₃Fe heterostructure. This study provides a reasonable design of the enhanced electronic structure and H adsorption energy down-shift from in-situ nanoarchitectonics of Ni₃FeN/Ni₃Fe heterostructure for enhanced HER performance.