Rationally construction of Dy2O3/g-C3N4 heterojunctions with largely enhanced photocatalytic hydrogen evolution activity

In this paper, Dy2O3/g-C3N4 photocatalysts with augmented photocatalytic hydrogen evolution activity were obtained by a pore impregnation method after baking. The samples were evaluated via scanning electron microscopy (SEM) and X-ray diffraction (XRD). Separation and migration efficiency of photogenerated carriers was analyzed using surface photovoltage spectroscopy (SPS), transient photocurrent density (TPR) and electrochemical impedance spectroscopy (EIS). Through low-temperature electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), nitrogen vacancies were successfully introduced into g-C3N4. All Dy2O3/ g-C3N4 samples display more stronger photocatalytic activity than the reference g-C3N4. Notably, 3 % DyO/CN exhibits the highest photocatalytic activity. The average photocatalytic hydrogen evolution rate over 3 % DyO/ CN reaches 9.9 mmol center dot g- 1 center dot h-1, which is nearly 3 times of that over the reference sample (3.3 mmol center dot g- 1 center dot h-1). In view of the observations, photocatalytic mechanism of Dy2O3/g-C3N4 heterojunction was rationally proposed.