Structural and compositional characteristics of electrodeposited indium-modified tin (Sn/In) electrodes at different indium concentrations

In this study, Indium-modified tin (Sn/In) electrodes were fabricated via electrodeposition using different InCl3 precursor concentrations (0.01, 0.05 and 0.10) to study their effects on surface morphology, elemental composition and crystal structure. The prepared electrodes were analysed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF) and X-ray diffraction. SEM images showed that the 0.01 M InCl3 electrode had patchy indium deposits with incomplete surface coverage, while the 0.05 M setup created a more uniform and continuous surface morphology. Increasing the concentration to 0.10 M led to particle clumping and higher surface roughness. Based on EDX data, the highest surface indium loading (15.86%) was achieved at 0.05 M, whereas XRF patterns XRF data showed a steady increase in bulk indium incorporation with higher precursor concentrations. The XRD patterns revealed that all Sn/In electrodes retained their tetragonal β-Sn crystal structure, and there was no other form of indium crystalline present in the sample. These results confirmed that the concentration of InCl3 has played a key role in controlling the structural and compositional characteristics of electrodeposited Sn/In electrodes. Based on the results obtained, the electrode modified with 0.05 M InCl3 offered the best balance between surface uniformity, indium loading and structural stability, making it a prospective candidate for subsequent electrochemical ethanol sensing applications.