Nickel, cobalt, and manganese oxides are easily obtainable non-noble metal catalysts for water splitting. However, the relationship between composition and catalysts’ performance still needs systematic studies. Herein, guided by theoretical calculations, a low overpotential, easily prepared Mn-doped Co3O4was deposited on graphite plates for water splitting. The 30% Mn-doped Co3O4(Co2.1Mn0.9O4) required the lowest overpotential for oxygen evolution reaction (OER), in which the Co2.1Mn0.9O4reached 20, 30, and 50 mA cm−2in the overpotentials of 425, 451, and 487 mV, respectively, with 90% IR compensation. Under overall water-splitting conditions, the current density reached 30 mA cm−2at an overpotential of 0.78 V without IR compensation. Charge density difference analysis illustrates that doped Mn provides electrons for O atoms, and that Mn doping also promotes the electron fluctuation of Co atoms. XPS analysis reveals that Mn-doping increases the chemical valence of the Co atom, and that the doped Mn atom also exhibits higher chemical valence than the Mn of Mn3O4, which is advantageous to boost the form of based-OOH* radical, then decrease the overpotential. Considering the particular simplicity of growing the Co2.1Mn0.9O4on graphite plates, this work is expected to provide a feasible way to develop the high-performance Co-Mn bimetallic oxide for water splitting.Keywords:water splitting;bimetallic oxides;Mn-doped Co3O4;DFT calculation
Jia-Ying Zhang,Lin-Feng Zhai,Sheng-Nan Tang,Hao-Li,Zhuo-Feng Hu,Min Sun
This study presents a novel nonradical catalytic oxidation system for targeted p-hydroxybenzene sulfonate (PHS) production from sulfonamides (SAs). A positive external electric field was applied to induce the in-situ activation of O 2 on Mn-doped Co 3 O 4 surface, with Mn-doping used to manipulate the reactivity of surface complexes. Theoretical simulations predicted CoMn-peroxides as thermodynamically favorable candidates for the targeted PHS production. Experimental validation achieved PHS yields of 18.4–32.6 % from five typical SA compounds. While 1 O 2 also actively participated in the oxidation of SAs, disruption of the 1 O 2 oxidation pathway significantly enhanced the PHS yields to 47.6–50.3 %. The intensity of electric field regulated the O 2 activation pathways by influencing the stability of CoMn-peroxides. This nonradical catalytic oxidation system demonstrated excellent catalyst reusability and environmental robustness for energy-efficient SAs removal and PHS recovery. These findings provide new insights into leveraging nonradical = pathways to advance catalytic oxidation technology for sustainable water management.
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