Electrocatalytic oxygen evolution surpassing benchmark RuO2 using stable, noble metal free vanadium doped hematite co-modified by NiFe Layered Double Hydroxide

Abstract

Exploring a low-cost, efficient and stable electrocatalyst to replace noble metal-based catalysts for oxygen evolution reaction (OER) is highly demanding for practical applications. Herein, we have proposed vanadium doping and co-modification of α- Fe2O3 utilizing NiFe LDH for noble metal free electrocatalytic oxygen evolution reaction (OER), which exceeds the performance of benchmark RuO2 under similar experimental conditions. Vanadium doping enhances the carrier density, whereas NiFe LDH contributes to the surface active sites for promoting water oxidation kinetics. A five-fold enhancement in electrochemically active surface area (ECSA) for α- Fe2O3:V-NiFe LDH (2.5 mF/cm2) compared to α- Fe2O3 (0.5 mF/cm2) is observed with a turnover frequency (TOF) of 7.6/s (α- Fe2O3:V-NiFe LDH). α- Fe2O3:V-NiFe LDH exhibited an impressive overpotential of 190 mV @ 10 mA/cm2 with corresponding Tafel slopes of 42 mV/dec. The electrocatalyst, α- Fe2O3:V-NiFe LDH also exhibited excellent durability for over 1000 cycles and continuous chronoamperometric responses for over 12 h at 25 mA/cm2, current density with an average Faradaic yield of 93%. Detailed electrochemical studies with long-term stability indicate the potential of as-synthesized composite α- Fe2O3:V-NiFe LDH for utilization as a heterogeneous catalyst for efficient oxygen evolution reaction.