Red phosphorus decorated and doped TiO2 nanofibers for efficient photocatalytic hydrogen evolution from pure water

Abstract

Highlights A new class of TiO2 nanofiber/red phosphorus (TiO2/RP) nanolayer core/shell heterostructure was fabricated by vaporization-deposition strategy. TiO2/RP exhibits enhanced photocatalytic pure water splitting performance. Decoration of RP extends the optical light harvesting ability.  P 5+ doping induced oxygen vacancies improve the charge separation efficiency.

A [001]‐Oriented Hittorf's Phosphorus Nanorods/Polymeric Carbon Nitride Heterostructure for Boosting Wide‐Spectrum‐Responsive Photocatalytic Hydrogen Evolution from Pure Water

“…As shown Figure b, the wavelength‐dependent photocatalytic HER rates of PCN@HP(0.4) under different light‐emitting diode (LED) light irradiation (Supporting Information, Figure S12) were pretty consistent with its optical absorption spectrum, indicating that the extended optical absorption by HP was responsible to photocatalytic HER activities in the wide‐spectrum visible light region. Importantly, the PCN@HP(0.4) composite ranks as the best photocatalyst for HER via pure water splitting, as compared to almost all the reported PCN and phosphorus‐based photocatalysts (Figure c; Supporting Information, Table S1) . Specifically, PCN@HP(0.4) displayed a quite high apparent quantum yield (AQY) up to 3.59 % at 420 nm.…”

“…Correspondingly, the colour changed from light yellow for PCN to dark brown for PCN@HP, which is even deeper than the red colour of HP (Supporting Information, Figure S10). These optical absorption and colour evolution indicated that the hybridization of PCN with HP can greatly improve the optical absorption ability to harvest visible light, thus contributing to the photocatalytic enhancement in the visible‐light region …”

“…(Reaction conditions: 50 mg of photocatalysts loaded with 3 wt % Pt as cocatalyst was dispersed in 150 mL of pure water). c) Comparison of photocatalytic HER activity from pure water on different PCN and phosphorus‐based photocatalysts …”

“…[8] However,t he rapid charge recombination and the sluggish charge mobility of RP restrict its photocatalytic efficiencyt o an unsatisfactory level. Although considerable efforts have been made to improve their photocatalytic performances, such as crystalline modification, [9] loading cocatalysts, [10] and constructing heterojunctions, [11] further improvement in efficiency still remains ag reat challenge.E xcept for those strategies of altering the physical properties,ithas been welldocumented that tailoring the crystallographic orientation of semiconductors is also beneficial for the enhanced photocatalytic performance by improving charge transfer ability, for TiO 2 ,W O 3 ,a nd BiVO 4 . [12] Fore xample,t he [010]orientated BiVO 4 photoanode obtained ah igher photocurrent as compared with the [121]-orientated one,owing to the faster electron mobility along [010] than [121] direction, which contributed to ahigher charge separation efficiency.…”

“…Moreover,t he previous reports about RP-based photocatalysts always focused on hydrogen evolution in the presence of hole sacrificial agents, such as methanol, triethanolamine,o ra scorbic acid, and unfortunately,R Pt hat could photocatalyze pure water splitting into hydrogen in the absence of sacrificial reagents is rarely reported. [7,9,11] Until very recently,the BP/RP hetero phase junction and BP/RP quantum dots were successfully developed to achieve photocatalytic water splitting without using sacrificial agents. [15] In this work, through af acile CVD strategy, [11] [001]oriented hexagonal-shaped Hittorfsp hosphorus (HP) nanorods with exposed {110} facets were vertically grown on polymeric carbon nitride (PCN) from am ixture of PCN and amorphous RP precursors.B yt uning the weight ratios of RP:PCN in precursor mixtures,t he optimized PCN@HP heterostructure exhibited the highest photocatalytic activity for pure water splitting, with hydrogen evolution reaction (HER) rates reaching 33.2 and 17.5 mmol h À1 under simulated solar light and visible light irradiation, respectively.I tw as seen that the strong electronic coupling between PCN and HP gave rise to the enhanced visible light absorption and the greatly accelerated photoinduced electron-hole separation and transfer along the [001] direction of HP nanorods, contributing to the improved photocatalytic activity for pure water splitting.…”