Facile Synthesis of Cobalt Oxalate/Silver Oxalate Composite for Boosting the Alkaline Water Oxidation Performance

Ghosh, Suptish (2021) Facile Synthesis of Cobalt Oxalate/Silver Oxalate Composite for Boosting the Alkaline Water Oxidation Performance. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Suptish Ghosh (16MS194)) 16MS194_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

The quest towards finding efficient Oxygen Evolution Reaction (OER) catalyst is still going on. The catalyst with a low overpotential, better stability and rapid kinetics are the key factors in designing an efficient OER catalyst. Herein, we developed a facile and efficient route for the synthesis of cobalt oxalate/silver oxalate composite via precipitation method at room temperature. The CoC2O4/Ag2C2O4 composite material has required an overpotential of 240 mV to reach the benchmark current density of 10 mA/cm2geo, with a Tafel slope value of 36 mV/dec. It has shown 36 hours of electrochemical stability and 90% faradic efficiency in 1(M) KOH. Incorporating a minimal amount of silver helped to reduce the overpotential up to 120 mV compared to CoC2O4.2H2O. Despite having a low Cdl (double layer capacitance) value of CoC2O4/Ag2C2O4 catalyst (1.84 mF/cm2), it displays better activity compared to CoC2O4 (15.12 mF/cm2). The pH-dependent study shows the proton reaction order (ρRHE) is 0.88, indicating a proton decoupled electron transfer (PDET) mechanism. After precondition, cobalt oxalate transforms to cobalt-oxyhydroxide and silver oxalate to silver oxide, respectively. Thus, the presence of silver engineers the intrinsic property of the composite material by exposing efficient active sites for OER.

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