Enhanced visible-light photocatalytic performance of Er³⁺ doped Bi₂O₃ for removing unsymmetrical dimethylhydrazine from water

The Er + doped Bi 2 O 3 photocatalytic membrane was synthesized via the sol-gel process. X-ray photoelectron spectroscopy (XPS) was utilized to analyze the surface chemical makeup of the synthesized samples, while photoluminescence (PL) spectroscopy was utilized to analyze their optical properties. The visible-light-driven photocatalytic activity was assessed through the degradation of unsymmetrical dimethylhydrazine (UDMH) in simulated wastewater systems. In consideration of potential future applications, investigations were also carried out on the photocatalytic reaction conditions and the stability of the system. XPS spectra indicated a shift in banding energy of Bi 4f and O 1s, suggesting the presence of Er in the doped Bi 2 O 3 . The photocatalytic tests demonstrated that the Er 3+ doped Bi 2 O 3 achieved markedly enhanced degradation efficiency over the undoped sample, reaching a maximum (87% at 180 min) at a specific doping concentration (1.0 at%). Kinetic analysis indicated pseudo-first-order behavior for the photodegradation reaction, and the highest rate constant was achieved with 1% Er 3+ dopant loading, about 2.1 times as much as that of the undoped photocatalyst. The proposed photocatalytic mechanism of Er 3+ doped Bi 2 O 3 is primarily ascribed to the enhanced separation efficiency of photogenerated electron-hole pairs induced by Er 3+ doping, a phenomenon that aligns well with the observations from photoluminescence (PL) spectral analysis.