A Floating Sheet for Efficient Photocatalytic Water Splitting

Abstract

effect of the upper catalysts. [ 6 ] The other one is the inconvenience originating from the intricate operations to extract the catalysts for recycling. Meanwhile powder loss may take place. [ 7 ] In order to overcome these weaknesses, we consider that photocatalysts may achieve more effi cient water splitting if they are integrated onto a substrate that can fl oat on water. [ 8 ] In this case, all the photocatalysts can absorb light energy effectively and the integrated sheet can be taken out from the water by a tweezer directly for recycling. Therefore, hydrophilic and low-mass carbon foam (CF) with 3D porous structure is selected as the fl oatable substrate. [ 9 ] Given that high carrier recombination rate is still a bottleneck of the photocatalytic technology, [ 10 ] the addition of a cocatalyst is regarded as a valid approach since the cocatalyst can act as a sink to trap the photoelectrons as well as active site for the reduction reaction. [ 11 ] Unfortunately, the state-of-theart cocatalysts are still noble metals (e.g., Pt, Au, Ru, or Pd) or their oxides that are rare and expensive. [ 12 ] Beyond them, cheap and effi cient cocatalysts have drawn more attention. Transition metal dichalcogenides (TMDs) have been more and more popular because of their fascinating physical and chemical properties. [ 13 ] The cocatalytic effect of molybdenum disulfi de (MoS 2 ) has been fully demonstrated already. [ 14 ] It was reported that tungsten-based TMDs possess better optical properties than molybdenum-based ones. [ 15 ] Moreover, an improved electrical conductivity and more active sites can be offered by selenium-based TMDs in electrocatalysis. [ 16 ] So tungsten diselenide (WSe 2 ) is expected to be a good cocatalyst. [ 17 ] Here, we demonstrate an effi cient solar photocatalytic water splitting using a fl oating sheet with a novel WSe 2 cocatalyst and nanodiamond-embedded Cu 2 O (NEC) photocatalyst. [ 18 ] This new-type artifi cial photocatalytic system makes full use of the incident light and avoids intricate operations in the recycling procedure. Meanwhile, the WSe 2 cocatalyst acts as an electron sink to promote electron-hole separation. Interestingly, this fl oating NEC/WSe 2 /CF structure achieves efficient water splitting upon simulated solar irradiation with an increased H 2 evolution rate, which is 13.2 times that of the powder-dispersing photocatalytic system. Overall, these fi ndings provide new ideas for the design of novel artifi cial photocatalytic systems.Solar photocatalytic water splitting has been a promising way to provide clean hydrogen energy. There are two weaknesses in the typical photo catalytic process in which photocatalysts are generally dispersing in water under stir. One is the inadequate utilization of light energy and the other one is the cumbersome operation in the recycling procedure. This study demonstrates an effi cient solar photocatalytic water splitting using a fl oating sheet with a novel WSe 2 cocatalyst. The sheet is fabricated by laser-depositing WSe 2 fi lm on a carbo...

In Situ Construction of Globe‐like Carbon Nitride as a Self‐Cocatalyst Modified Tree‐like Carbon Nitride for Drastic Improvement in Visible‐Light Photocatalytic Hydrogen Evolution

“…On the basis of the plot of the transformed Kubelka–Munk function ( αhυ ) 1/2 versus the energy of exciting light ( hυ ) (Figure S9), the band gaps of CN (B), CN (G/S), and CN (G/T) were estimated to be 2.55, 2.74, and 2.71 eV, respectively. By linearly extrapolating the leading edge of the valence band (VB) of the X‐ray photoelectron spectra of CN (B), CN (G/S), and CN (G/T) to the base line (Figure a), the VB levels were determined to be+1.88,+2.16, and+1.80 eV, respectively . The band gaps of CN (B), CN (G/S), and CN (G/T) were determined to be 2.55, 2.74, and 2.71 eV, respectively, with corresponding conduction band (CB) positions at −0.67, −0.58, and −0.91 eV, respectively (Figure S10).…”

“…[32] Another reason for this increasedb and gap is the unique morphological structures of the globe/strip-like and globe/tree-like carbon-nitrogen mate- (Figure 3a), the VB levels were determined to be + 1.88, + 2.16, and + 1.80 eV,r espectively. [33] The band gaps of CN (B), CN (G/S), and CN (G/T) were determined to be 2.55, 2.74, and 2.71 eV,r espectively,w ith corresponding conduction band (CB) positions at À0.67, À0.58, and À0.91 eV,r espectively ( Figure S10). Relative to the valuesf ound for CN (B), the VB potential of CN (G/S) and the CB potentialofC N(G/T) are upshifted by approximately 0.28 and 0.24 eV,r espectively,w hich may have led to al arger thermodynamic driving force duringp hotocatalytic hydrogen production.…”

In Situ Decoration of ZnxCd1−xS with FeP for Efficient Photocatalytic Generation of Hydrogen under Irradiation with Visible Light

“…The linear sweep voltammetry (LSV) test is used to explore the electrocatalytic activity of the sample for HER without light irradiation. Typically, smaller onset potential or bigger current at the same potential would be corresponding to higher efficiency for HER . As shown in Figure d, pure FeP exhibit smaller onset potential with high current, suggesting its good activity in HER.…”

Novel 3D Semiconducting Open‐Frameworks based on Cuprous Bromides with Visible Light Driven Photocatalytic Properties

“…It should be noted that the strong separating ability of Ag nanoparticles for the photo‐induced carriers plays an important role in the photocatalytic activities and photochemical stabilities of the Ag/AgX photocatalyst. In other words, the introduction of charge separating components into silver halogenides is able to effectively accelerate the separation process of the photo‐induced carriers of Ag/AgX photocatalyst, which will prevent the photolysis reactions of AgX and increase the photochemical stabilities . However, in these strategies, a big challenge is to understand the structure–property relationship because of the mixed compositions without clear crystal structures.…”