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. - Highlights: • Ni²⁺-modified with higher photodegradation ability was synthesized. • ·OH radicals were the main active species in the oxidation of MO. • The doping of Ni²⁺ in Ag₃PO₄ is responsible for the enhanced activity.