Mesoporous TiO2 electrocatalysts synthesized by gliding arc plasma for oxygen evolution reaction

Addressing the needs of CO2 reduction and fuel cell vehicles, green hydrogen is vital and can be obtained from polymer electrolyte membrane electrolyzer using renewable electricity. The oxygen evolution in acid over noble catalysts remains its capital cost, hence which impedes it from being deployed. Semiconductor TiO2 was randomly examined in 2D film electrode but is rarely investigated in state-of-the-art 3D porous electrode using Nafion(R) binder due to the incapability of electrochemical window. Here we demonstrate mesoporous TiO2 for oxygen evolution which is synthesized by gliding arc plasma. Our mesoporous TiO2 (mT, mTc) catalysts outperform commercial TiO2 (cT), in terms of the decrease of 800 mV in onset potential, 13.4 times current at the approximate starting potential (of Tafel slope region), 4.7 times current (of overall reaction rate) at 2.652 V vs RHE. Of interest the rationale behind the remarkable activity is the nature of the electrode-solution interface, which is triple phase boundary (TPB), revealed by inherent parameters of solution resistance R (s) and double-layer capacitance C (d). Both R (s) and the fraction in voltage drop of resistance and capacitance ( f (Rs), f (Cd)), are consistent with apparent parameters such as ionomer/catalyst ratio (I/C), catalyst, and activity. The suitable electrochemical potential window allows semiconductor TiO2 in 3D porous electrode examined. More importantly, the inherent parameters are disclosed to correlate with the TPB, which provides electrochemistry and plasma communities with such new insights.

Automated summary

This study demonstrates the superior performance of mesoporous TiO2 (mT, mTc) catalysts, synthesized by gliding arc plasma, in oxygen evolution compared to commercial TiO2 (cT), with lower onset potential, higher current, and faster reaction rate. The activity is attributed to the triple phase boundary (TPB) of the electrode-solution interface, with consistent parameters such as ionomer/catalyst ratio, catalyst, and activity. The findings provide new insights for the electrochemistry and plasma communities.