Photocatalytic Activity And Mechanism Of H₂ Production Of Surface Decorated Red Phosphorus Over Water Splitting

Photocatalytic technology by converting solar energy into non-polluting,high-combustion value hydrogen（H₂）is considered to be an effective solution to energy shortage.The construction of photocatalyst with high activity is the core of photocatalytic technology.At present,most of semiconductor materials display the disadvantages of narrow light response,high price,wide band gap and secondary pollution to the environment.The elemental red phosphorus（RP）photocatalyst has become one of the most promising photocatalysts because of its wide light absorption range,low price and narrow band gap energy.However,the fast recombination rate of photocarriers greatly inhibits the hydrogen production performance of RP,and further limiting its practical application.Therefore,reducing the recombination rate of photocarriers meanwhile accelerating the separation and migration of photocarriers are the primary tasks to improve the performance of RP under wide spectral range.In this paper,RP was modified by constructing RP-based heterojunction to effectively accelerate the separation efficiency of photocarriers,and thus improve its photocatalytic performance of H₂ production.The main research contents and conclusions are presented as follows:（1）The NiO/RP composite was synthesized by using a low-temperature calcination method.The structure and properties of as-prepared NiO/RP composites were analyzed by XRD,XPS,DRS,EPR and I-V curves,etc.The photocatalytic activity of H₂production over NiO/RP composite was explored under the visible light（λ≥420 nm）with methanol as a sacrificial agent.The results showed that the NiO/RP composite exhibited higher photocatalytic activity than pure NiO and RP from visible to near infrared light irradiation.This is mainly attributed to the high separation and migration of photocarriers via a Z-scheme mode.Therefore,the construction of the Z-scheme NiO/RP heterojunction is an efficient strategy to improve the activity of RP for photocatalytic H₂ production.（2）Novel Ni（OH）₂/RP photocatalyst was prepared via an electrostatic self-assembly strategy.Under visible light irradiation（λ≥420 nm）,the amounts of H₂ evolution on Ni（OH）₂/RP composites were investigated using methanol as sacrificial agent.The results showed that loading a little amount of Ni（OH）₂ on the surface of RP significantly increased the H₂ production activity of RP.The Ni（OH）₂ acted as the trapping site of electrons to accelerate the photocarriers separation of RP.This work provides a new idea for simply assembling transition metal hydroxides decorated RP-based composite photocatalyst with highly efficient H₂ production activity.