High-performance electrocatalytic degradation of crystal violet using graphene hydroxide-modified PbO2 electrode

Abstract

Electrocatalytic degradation of crystal violet using PbO₂/GOH electrodes (GOH: graphene hydroxide) has been carried out. GOH was synthesized via exfoliation, hydrothermal, and ultrasonication, while the PbO₂/GOH electrode was prepared using EPD (electrophoretic deposition). GOH exhibits a single peak at 266 nm, high intensity of CC and OH stretching vibrations, and an I_D/I_G ratio of 0.55 in the Raman spectrum. The XRD pattern shows peak broadening and a 98.22 % decrease in intensity, while the SEM image shows aggregated graphene sheets, a slightly rough surface, and porosity in the form of gaps. The TEM image shows thin GOH layers, and SEM-EDX data indicate that GOH has a C/O ratio of 2.04. The interaction between PbO₂ and GOH is marked by new bands at 683, 843, and 1409 cm⁻¹. The morphological change of PbO₂ from fine to coarse particles in PbO₂/GOH was observed via SEM-EDX, indicating interaction between PbO₂ and GOH. Based on SEM-EDX results, the C/O/Pb ratio in PbO₂/GOH is 79.36/17.72/1.46 %. The cyclic voltamogram of PbO₂/GOH shows that the current increases by 73.33 % and the voltage decreases by 23.53 %. The electrodegradation of the crystal violet using PbO₂/GOH within 10 min can remove 99 % of the dye, reduce BOD by 94.08 %, and COD by 95.79 %, while in actual wastewater, it can remove 96 % of the dye and reduce BOD and COD by 97 % and 98 %, respectively. The electrode can be reused up to 10 cycles, and the dissolution of Pb²⁺ ions decreased by 71.66 % compared to unmodified PbO₂ electrodes.