Electrodeposited manganese carbonate as an electrocatalyst for hydrogen evolution reaction in acidic medium.

The electrolysis of water is the key method for hydrogen production but the high overpotential necessitates electrocatalysts. Traditionally, Pt is used, but it is scarce and costly. Herein, MnCO 3 is unveiled as an electrocatalyst for the production of hydrogen. MnCO 3 is electrodeposited onto pencil graphite by chronoamperometric method and confirmed by XRD and vibrational spectroscopic studies. MnCO 3 electrodeposited for 15 min at 2 V demonstrates a good HER activity (overpotential of 123 mV to reach 10 mA cm−2) in 0.5 M H 2 SO 4 with a Tafel slope of 79 mV dec−1. In addition, MnCO 3 exhibited good stability during continuous operation (over 3000 cycles and 14 h). Though MnCO 3 requires higher overpotential than the benchmark catalyst (Pt/C) to reach 10 mA cm−2, it outperforms Pt/C at higher current density (≥75 mA cm−2) demonstrating that MnCO 3 could be used as an electrocatalyst to produce H 2 at a high rate from acidic medium. [Display omitted] • MnCO 3 is electrodeposited onto pencil graphite by chronoamperometry method. • MnCO 3 electrodeposited at 2 V demonstrates a good HER activity in 0.5 M H 2 SO 4. • MnCO 3 exhibits good stability (over 3000 cycles and 14 h of continuous operation). • MnCO 3 surpassed the performance of Pt/C at 100 and 200 mA cm−2 [ABSTRACT FROM AUTHOR]