Construction and preparation of coated Z-scheme NaGdF4:Nd3+,Yb3+,Tm3+@CdS-Pd@NiO photocatalyst with core-shell structure for organic pollutant degradation with synchronous hydrogen evolution

A coated Z-scheme NaGdF 4 :Nd 3+ ,Yb 3+ ,Tm 3+ @CdS-Pd@NiO photocatalyst with core-shell structure is prepared by hydrothermal and coprecipitation methods. NaGdF 4 :Nd 3+ ,Yb 3+ ,Tm 3+ as excellent up-conversion luminescent material can convert infrared light into visible light, broadening the light response range of CdS. Pd nanorods act as conductive channels and co-catalysts, leading to successful construction of titled photocatalyst, increasing contact area between two monomer photocatalysts, promoting transfer of photo-generated electrons. It also provides a large oxidation surface for organic pollutant degradation. The performance of prepared photocatalyst is assessed by Congo red degradation and hydrogen production . The emission spectrum and energy conversion mechanism of NaGdF 4 :Nd 3+ ,Yb 3+ ,Tm 3+ are investigated. The photocatalyst with 3:1 NaGdF 4 :Nd 3+ ,Yb 3+ ,Tm 3+ @CdS-Pd and NiO mass ratio has a preeminent activity. Congo red degradation ratio and hydrogen production amount reach 92.48% and 653.06 µmol/g, respectively, under simulated sunlight irradiation for 180 min. The possible mechanism of organic pollutant degradation with synchronous hydrogen production caused by titled photocatalyst is proposed.