context: Unlike DC voltage exfoliation, square-wave voltage uses bulk antimony, bismuth and their compounds as the anode and platinum wire or foil as the cathode, and changes the voltage direction to perform electrochemical exfoliation in an electrolytic solution of Na2SO4 or Li2SO4. This process mainly uses oxygen-containing free radicals produced by electrolysed water to assault large pieces of antimony or bismuth or their compounds in the anode, and SO42− intercalates into the interlayer. Subsequently, the gas generated between the layers of the bulk layered material further expands, and finally 2D antimony or bismuth or its compound is obtained in the electrolyte. In 2020, Marzo et al. elucidated the possible mechanism of changing the voltage exfoliation of 2D Sb and Sb2Te3. As shown in Fig. 4b, this exfoliation process comprises four different stages. In the first stage, oxygen-containing free radicals produced by the electrolysis of water on the anode bulk 2D material react with the edges and boundaries, creating bumps, cracks and holes in the bulk 2D material. Next, the small cations (H+, Li+ and Na+) intercalate into the gaps and holes formed in the previous bulk 2D material, initializing a slight and preliminary expansion of the 2D sandwich. When the conversion voltage is −5 V, the SO42− intercalation layer enters the interlayer of the bulk 2D material. Finally, the gases (H2, O2 and SO2 formed in these redox processes) generated by the insertion of ions between the 2D bulk material layers promote the exfoliation of the 2D material and disperses it into the electrolyte (Fig. 4b).
answer:  platinum wire or foil