S,P Co-Doped NiFe-Based MOF-Derived Composite as Bifunctional HER/OER Electrocatalysts

Metal-organic frameworks (MOFs) have attracted considerable research interest as versatile templating agents for synthesizing transition metal compounds, particularly in electrocatalytic water splitting applications due to their tunable spatial architectures and compositional flexibility. This study investigated the in situ growth of sulfur-phosphorus codoped NiFe-based MOF catalysts on nickel foam (NF) substrates (FeNi3-CPS/NF) and their bifunctional activities toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH. Electrochemical measurements demonstrate that the FeNi3-CPS/NF catalyst exhibits remarkable catalytic performance with low overpotentials of 136 mV for HER and 75 mV for OER, and low Tafel slopes of 30.97 (HER) and 8.49 mV dec-1 (OER), respectively. The charge transfer resistance (Rct) values reach 2.328 Ω during HER and 2.149 Ω during OER, highlighting efficient electron transfer. The electrochemical active surface areas (ECSA) were determined as 1200 cm2 for HER and 1425 cm2 for OER. Stability assessments reveal excellent durability under both HER and OER conditions, with current retention rates of 86.32% and 80.71% respectively after prolonged electrolysis. These findings collectively establish FeNi3-CPS/NF as a promising bifunctional electrocatalyst combining high catalytic activity with exceptional stability for overall water splitting applications. The innovative integration of heteroatom doping within the MOF architecture offers new design strategies for advanced energy conversion materials.