A novel Ni2+-doped Ag3PO4 photocatalyst with high photocatalytic activity and enhancement mechanism

Ni2+-doped Ag3PO4 (Ni2+-Ag3PO4) photocatalysts with superhigh activity for photodegradation of organic pollutants were prepared by a simple hydrothermal method. The photocatalysts were characterized with X-ray powder diffractometry, transmission electron microscopy, ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. The photocatalysts were evaluated by methyl orange (MO) photodegradation experiments under visible light irradiation (λ > 420 nm). Comparative analysis showed the optimal doping dosage was 0.05 mol/L Ni2+. The optimal Ni2+-Ag3PO4 has an MO photodegradation rate constant four times larger than pure Ag3PO4. The photocatalytic ratio of 40 mg/L MO over the optimal Ni2+-Ag3PO4 after 10 min is 89%, which indicates excellent photocatalytic ability in high-concentration MO solutions. The Ni2+ doping into Ag3PO4 can increase the level of band gap, and accelerate the utilization of photons and the separation of photo-generated charges. Therefore, the Ni2+ doping into Ag3PO4 is responsible for the enhancement of photocatalytic ability.