Mn2+-doped Co3Si2O5(OH)4 serpentine nanosheets with tuned d-band centers for efficient oxygen evolution in alkaline and neutral electrolytes

Serpentine structured Co3Si2O5(OH)(4) is inexpensive, chemically stable, and electrochemically active in oxygen evolution reactions (OER). However, the OER activity of Co3Si2O5(OH)(4) materials is still unfavorable due to the low active sites. Here, Mn2+-doped Co3Si2O5(OH)(4) serpentine nanosheets with tuned d-band centers are achieved for efficient oxygen evolution in alkaline and neutral electrolytes. The CoxMn3-xSi2O5(OH)(4) serpentine nanosheets are synthesized by a simple hydrothermal method. The optimized Co2.4Mn0.6Si2O5(OH)(4) serpentine nanosheets showed favorable OER overpotentials as well as stable durability in KOH solution and phosphate buffer solution, which were superior to most of the Co-based and Mn-based OER electrocatalysts. The in situ Raman spectroscopy shows that the materials are kept well in the electrochemical OER environments. Further density functional theory shows that the d-band center of CoxMn3-xSi2O5(OH)(4) serpentine nanosheets is shifted more upward in comparison with pristine Co3Si2O5(OH)(4). The changes in the d-band center increase the adsorption of intermediates, optimize the reaction steps, and lower the energy barriers of the OER. That is the main reason for the OER enhancement Mn2+-doped Co3Si2O5(OH)(4). This work gives an efficient strategy to design cheap and stable electrocatalytic materials for OER in a broad pH environment.