Three-Dimensional Mn-Substituted CuCo₂S₄-MWCNT for Electrocatalytic Oxidation of Glycerol

Given its cost-effectiveness and favorable electrochemical properties, Cu–Co spinel sulfide was selected as the electrode material for an in-depth investigation. The Mn-substituted CuCo 2 S 4 -multiwalled carbon nanotube (MWCNT) composite was then synthesized via a solvothermal approach, targeting the electrocatalytic oxidation of glycerol. Physical and electrochemical characterizations revealed that the CuCo 0.5 Mn 1.5 S 4 –MWCNT composite demonstrated a superior catalytic performance. This was evidenced by its low overpotential, reduced electrochemical impedance (17.8 Ω), and smaller Tafel slope (60 mV dec –1 ), along with good long-term stability (retention rate of 73%) and tolerance under operational conditions. The enhanced performance of the CuCo 0.5 Mn 1.5 S 4 –MWCNT composite is likely attributed to Mn ion substitution. This substitution not only elevates the relative surface concentration of Co 3+ and Mn 3+ in the sulfur spinel structure but also increases the O ads /O latt ratio to 1.2. Density functional theory (DFT) calculations further support that Mn substitution significantly boosts the electrical conductivity of the composite. Moreover, the integration of highly conductive MWCNTs as a structural framework results in a stable 3D architecture within the CuCo 0.5 Mn 1.5 S 4 –MWCNT composite. This research presents a promising strategy for electrocatalytic glycerol oxidation, leveraging hybrid materials composed of transition-metal sulfides and carbonaceous substrates as conductive platforms.