Ti₃C₂T_x MXene-enhanced Cu₂S nanosheet composite for selective electrochemical conversion of waste crude glycerol to glyceric acid

In this work, we present a straightforward approach to synthesizing a highly active, sandwich-like composite electrocatalyst consisting of Cu₂S/crude glycerol-derived carbon/Ti₃C₂Tₓ MXene for glycerol electrooxidation (GEOR) and crude glycerol electrooxidation reaction (CGEOR). Cu₂S nanosheet arrays are grown directly on sulfur-doped crude glycerol-derived carbon (CGC) via a low-temperature co-reduction method, followed by the incorporation of MXene through a mechanochemical approach. The composite material’s physicochemical properties were comprehensively analyzed using SEM/EDX, TEM, XRD, and XPS. Electrochemical studies revealed that the Cu₂S/CGC/MX electrode exhibited exceptional catalytic activity, achieving a voltage of 0.46 V at 50 mA/cm² with a turnover frequency (TOF) of 13.1 s⁻¹ , significantly outperforming Cu₂S (0.71 V), Cu₂S/CGC (0.58 V), and MXene (0.97 V), highlighting the synergistic effect of the composite structure. High-performance liquid chromatography (HPLC) analysis confirmed 100 % glycerol conversion, with a remarkable 94 % selectivity toward glyceric acid and a Faradaic efficiency of 60 % for GEOR, while CGEOR achieved 80 % selectivity. Density functional theory (DFT) analysis attributed the superior conversion efficiency to the MXene-enhanced catalytic surface. Post-electrolysis analysis via SEM/EDX and XPS confirmed controlled surface reconstruction due to sulfur leaching in the composite electrode compared to without MXene, highlighting the role of MXene in the Cu₂S electrode. The integration of crude glycerol as both a carbon precursor and fuel offer a sustainable approach to waste valorization and alternative energy generation, demonstrating the potential for efficient, eco-friendly electrocatalysts in renewable energy applications.