Abstract <p>The Y₂O₃ catalyst was prepared by using citric acid complexation method and the decorated Y₂O₃ catalyst was obtained through industrial carbonic acid (CA) impregnation. The phase structure characterization confirmed that the cubic phase of Y₂O₃ was not destroyed by CA impregnation, but C–O functional groups were still present on the surface. After impregnating with CA, the surface contour of Y₂O₃ particles becomes clearer and the agglomeration phenomenon is weakened. The average particle size of the decorated Y₂O₃ is approximately 60 nm. Element mapping characterization also confirmed the presence of a small amount of C element in the decorated Y₂O₃. The photoresponse capability of the decorated Y₂O₃ catalyst can be extended from 400 nm to a visible light range of 800 nm. The optical bandgap value of the decorated Y₂O₃ decreased from the undecorated 3.15 to 2.88 eV. The degradation experiment carried out with chlortetracycline hydrochloride as the degradation target pollutant found that when the catalyst content was 1 g/L, the pollutant concentration was 150 mg/L and pH 5, the degradation percentage of the decorated Y₂O₃ catalyst reached 94.6%. Experiments and band theory have confirmed that the decorated Y₂O₃ catalyst has a high photocatalytic activity, which is related to the free radicals and its point of zero charge (PZC). The use of this new processing technology enables the expansion of the application range of wide bandgap semiconductor materials in the field of photocatalysis.</p>