Manganese Carbonate (Mn₂(CO₃)₃) as an Efficient, Stable Heterogeneous Electrocatalyst for the Oxygen Evolution Reaction

Abstract

With the growing population and energy demand, there is an urgent need for the production and storage of clean energy obtained from renewable resources. Water splitting electrocatalytically is a major approach to obtain clean H 2 . The efficiency, stability, and slow kinetics of anode materials developed so far do not fit the commercial application of the water oxidation reaction. To develop an efficient energy conversion catalyst, particularly for the oxygen evolution reaction (OER) herewith, Mn 2 (CO 3 ) 3 was electrodeposited on a Ni foam (NF) electrode surface by the chronoamperometric technique. The deposited Mn 2 (CO 3 ) 3 /NF was characterized using various surface characterization techniques. The electrochemical behavior of the Mn 2 (CO 3 ) 3 /NF-deposited electrode toward the OER was studied using electrochemical methods in KOH (pH 14) and NaHCO 3 (pH 8.3) electrolytes. The Mn 2 (CO 3 ) 3 /NF electrode showed a lower overpotential than CO 3 /NF and NF electrodes in the KOH/NaHCO 3 media. The Mn 2 (CO 3 ) 3 /NF electrode performs high electrocatalytic water oxidation with an overpotential of 360 mV at a current density of 10 mA•cm −2 . This overpotential is much lower than those of CO 3 /NF (460 mV) and bare NF (520 mV), with good long-term stability in the KOH medium without any catalytic degradation after 100 CV cycles and 15 h chronoamperometric studies. The stability of the electrodeposited Mn 2 (CO 3 ) 3 on the NF electrode was determined by X-ray photoelectron spectroscopy. Thus, the Mn 2 (CO 3 ) 3 /NF catalyst is suitable for the oxygen evolution reaction.

Manganese carbonate as an efficient electrocatalyst for the conversion of ammonia (NH4+/NH3) to dinitrogen

“…Mn 2 (CO 3 ) 3 shows its characteristics absorption bands at 1410 cm −1 , 864 cm −1 , and 718 cm −1 . 32 Also, the CO stretching band is observed at 1713 cm −1 along with the CO 3 2− asymmetric stretching band at 1410 cm −1 . The two absorption bands at 864 cm −1 and 718 cm −1 are corresponding to the out-of-plane and in-plane bending modes, respectively.…”

“…Presence of Mn 3+ and Mn 4+ were distinguished from the peak at 642.1 eV along with a tiny peak at 644.9 eV respectively in the Mn 2p 3/2 peak. 32 The presence of oxygen in the deposited Mn 2 (CO 3 ) 3 can be identified from the O 1s spectrum as shown in Fig. 1e.…”

“…Similarly, the peak at 529.2 eV can be ascribed to the oxygen binding with the metal atom and the peak at 531.9 eV can be assigned to the lattice oxygen of CO 3 2− ions. 32 The C 1s spectrum displays two binding energy peaks at 285 eV and 289 eV, which can be corelated to the presence of C–O and CO groups as displayed in Fig. 1f.…”

“…1f. 32 The atomic percentage values of Mn 2 (CO 3 ) 3 determines the presence of Mn with 5.86%, C with 35.3% and O with 56.5%, respectively. Additionally, powder XRD analysis was performed to determine the crystalline nature of electrodeposited Mn 2 (CO 3 ) 3 on a stainless-steel surface and the XRD spectrum for the same is shown in Fig.…”

“…30 Metal carbonates serve also as promising electrode catalysts for oxidation processes. 31,32 The carbonate ligand forms complexes with transition-metal cations by acting as a s-donor and hence, stabilize the high oxidation states of metals. 33 Several rst-row transition metals e.g.…”