Synergetic adsorption and photocatalysis performance of g-C3N4/Ce-doped MgAl-LDH in degradation of organic dye under LED visible light

Adopting a facile one-step solvothermal method, CN/MgAl0.80Ce0.20-LDH, a lamellate composite of graphitic carbon nitride (g-C3N4, CN) and Ce-doped MgAl-layered double hydroxide (LDH), was synthesized. Profiting from the combined effect of Ce-doping and CN-LDH composition, CN/MgAl0.80Ce0.20-LDH possesses large specific surface area (52.71 m2 g−1) and high separation efficiency of photogenerated charge. When used to remove organic dye Congo red (CR), the composite exhibits enhanced efficiency which can be attributed to the synergetic performance of adsorption and photocatalysis. As a result, ~49% CR (50 mg L−1) can be adsorbed by CN/MgAl0.80Ce0.20-LDH and the CR degradation efficiency exceeds 90% within 180 min under light-emitting diode (LED) visible light irradiation, which is much higher than that of pristine CN (48.77%). The augmented surface area and proliferated active sites benefit the increase of adsorption capacity. The enhanced photocatalytic performance can be attributed to the efficient transmission of photogenerated electrons and holes between CN and MgAl0.80Ce0.20-LDH. Electrochemical impedance spectroscopy (EIS) analysis and photoluminescence (PL) analyses confirmed the effective separation of photogenerated electron-hole pairs in CN/MgAl0.80Ce0.20-LDH, while electron spin resonance (ESR) results verified the derivation of superoxide radicals (·O2-) species amid CR photocatalytic degradation.