Dual-functional MnS2/MnO2 heterostructure catalyst for efficient acidic hydrogen evolution reaction and assisted degradation of organic wastewater

The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy. Herein, MnS2/MnO2-CC heterostructure dual-functional catalysts with ultrathin nanosheets were prepared by a two-step electrodeposition method for efficient acidic hydrogen evolution reaction (HER) and degradation of organic wastewater (such as methylene blue (MB)). The electronic structure of Mn atoms at the MnS2/MnO2-CC heterostructure interface is reconfigured under the joint action of S and O atoms. Theoretical calculations show that the Mn d-band electron distribution in MnS2/MnO2-CC catalyst has higher occupied states near the Fermi level compared to the MnO2 and MnS2 catalysts, which indicates that MnS2/MnO2-CC catalyst has better electron transfer capability and catalytic activity. The MnS2/MnO2-CC catalysts require overpotential of only 66 and 116 mV to reach current density of 10 and 100 mA cm−2 in MB/H2SO4 media. The MnS2/MnO2-CC catalyst also has a low Tafel slope (26.72 mV dec−1) and excellent stability (the performance does not decay after 20 h of testing). In addition, the MB removal efficiency of the MnS2/MnO2-CC catalyst with a better kinetic rate (0.0226) can reach 97.76%, which is much higher than that of the MnOx-CC catalyst (72.10%). This strategy provides a new way to develop efficient and stable non-precious metal dual-functional electrocatalysts for HER and organic wastewater degradation.