Improved oxygen evolution reaction performance of NiCo-metal organic framework/carbon paper catalysts in anion exchange membrane water electrolysis via ultrafast atmospheric-pressure plasma jet processing

A NiCo metal organic framework (MOF) was solvothermally synthesized on carbon paper (CP) (NiCo-MOF/CP) as a catalyst for the oxygen evolution reaction (OER). The NiCo-MOF/CP catalyst modified using ultrafast atmospheric-pressure plasma jet (APPJ) treatment improved the OER performance. Through APPJ treatment for 60 s, high-valence oxidation states (Ni³⁺, Co³⁺) and oxygen vacancies can be introduced on the surface of the electrocatalyst while maintaining the MOF structure. NiCo-MOF/CP electrocatalysts treated for 60 s exhibited the best OER activity, with the overpotential decreasing from 843 mV to 680 mV at a current density of 100 mA/cm². The double-layer capacitance (2C_dl) value increased from 9.55 mF/cm² to 45.77 mF/cm², indicating that the APPJ treatment significantly increased the active surface area. Testing the electrocatalyst as an anode (OER) electrode in anion exchange membrane water electrolysis (AEMWE) at 25 °C, plasma treatment increased the energy efficiency from 77.14% to 80.69% at a current density of 100 mA/cm². At 70 °C and a current density of 500 mA/cm², the specific energy consumption reached 4.37 kWh/m³, and the cell voltage dropped to 1.71 V, demonstrating excellent low voltage performance. The durability test results show that after plasma treatment, the degradation rate decreased from 718.3 μV/h to −118.3 μV/h. These results indicate that APPJ treatment can improve the performance of OER electrocatalysts in AEMWE.