Graphitic carbon nitride (g-C3N4) quantum dots (CNQDs) were prepared from bulk g-C3N4 directly by a thermal-chemical etching process. The CNQDs show strong blue emission as well as upconversion behavior, which can be used as universal energy-transfer components in visible-light-driven metal-free photocatalytic systems.

0D/2D heterojunctions,e specially quantum dots (QDs)/nanosheets (NSs) have attracted significant attention for use of photoexcited electrons/holes due to their high charge mobility.H erein, unprecedent heterojunctions of vanadate (AgVO 3 ,B iVO 4 ,I nVO 4 and CuV 2 O 6 )Q Ds/graphitic carbon nitride (g-C 3 N 4 )N Ss exhibiting multiple unique advances beyond traditional 0D/2D composites have been developed. The photoactive contribution, up-conversion absorption, and nitrogen coordinating sites of g-C 3 N 4 NSs,h ighly dispersed vanadate nanocrystals,aswell as the strong coupling and band alignment between them lead to superior visible-light-driven photoelectrochemical (PEC) and photocatalytic performance, competing with the best reported photocatalysts.T his work is expected to provide anew concept to construct multifunctional 0D/2D nanocomposites for al arge variety of opto-electronic applications,n ot limited in photocatalysis.For decades,0-dimensional (0D) semiconductive QDs have attracted great attention due to their unique advantages of small size (< 10 nm), large surface area, short effective charge-transfer length and size-tunable optoelectronics, [1] which make them highly promising in using the photoexcited charges in the field of photodetectors,p hototransistors, photovoltaic devices,a nd photocatalysts.[2] However,s everal drawbacks largely restrict their practical applications. [1a,2b, 3] First, QDs are vulnerable to self-aggregation;a bundant surface defects make them unstable in comparison with their bulk counterparts;m oreover,t he high photoluminescence of QDs results in heavy recombination of photoexcited charges.[4] One of the most efficient routes to solve these problems is to load QDs onto ultrathin 2-dimensional (2D) NSs (e.g. graphene) to form a0 D/2D nanocomposite. [5] Interactions between two moieties can make QDs more dispersive and stable,w hile the accelerated charge transfer facilitated by 2D NSs can effectively quench the photoluminescence of QDs,thereby suppressing the recombination of photoexcited charges.T hus,s ubstantially enhanced optoelectronic performance is achieved by the 0D/2D composites in efficient utilization of photoexcited charges. [5] Recently,0 D/2D composite photocatalysts/photoelectrodes have been greatly developed, in which the coupling of QDs and graphene NSs is the most successful illustration. Due to the large surface area and high electrical conductivity of graphene,t he loaded semiconductive QDs (nanocrystals) are endowed with superior charge transfer and separation capability,t hereby presenting greatly promoted photocatalytic activity or/and photocurrent.[6] Forexample,Y uand coworkers [6a] loaded TiO 2 nanocrystals (< 10 nm) on graphene NSs,which displayed the best apparent quantum efficiency of 9.7 %a t3 65 nm;F ang et al.[6b] and Liu and co-workers [6c] respectively incorporated CdS QDs onto graphene NSs, bringing enhanced photocatalytic and PEC performance. However,t he largely consumed graphene NSs (volume ratio even higher than 50...

A new single elemental heterostructure of black–red phosphorus was prepared, which exhibited high visible-light-driven photocatalytic activity comparable to that of CdS.

Earth-abundant red phosphorus was found to exhibit remarkable efficiency to inactivate Escherichia coli K-12 under the full spectrum of visible light and even sunlight. The reactive oxygen species (•OH, •O2(-), H2O2), which were measured and identified to derive mainly from photogenerated electrons in the conduction band using fluorescent probes and scavengers, collectively contributed to the good performance of red phosphorus. Especially, the inactivated-membrane function enzymes were found to be associated with great loss of respiratory and ATP synthesis activity, the kinetics of which paralleled cell death and occurred much earlier than those of cytoplasmic proteins and chromosomal DNA. This indicated that the cell membrane was a vital first target for reactive oxygen species oxidation. The increased permeability of the cell membrane consequently accelerated intracellular protein carboxylation and DNA degradation to cause definite bacterial death. Microscopic analyses further confirmed the cell destruction process starting with the cell envelope and extending to the intracellular components. The red phosphorus still maintained good performance even after recycling through five reaction cycles. This work offers new insight into the exploration and use of an elemental photocatalyst for "green" environmental applications.

The structures and local environments of boron species in B-doped and (B, N)-codoped TiO2 photocatalysts have been investigated by solid-state 11B NMR spectroscopy in conjunction with density functional theory (DFT) calculations. Up to seven different boron sites were identified in the B-doped anatase TiO2, which may be classified into three categories, including interstitial, bulk BO3/2 polymer, and surface boron species, and has been supported by results obtained from FT-IR and XPS spectroscopy as well as from DFT calculations. Two types of interstitial borons, namely the tricoordinated (T*)- and pseudotetrahedral-coordinated (Q*) borons, were observed in addition to the two types of bulk BO3/2 polymer and three types of surface B, in good agreement with experimental data. Further density of state analyses revealed that, compared to undoped TiO2, the T* species in boron-doped TiO2 are solely responsible for the observed increase in energy band gap, whereas the presence of Q* species tend to lead to a decrease in band gap and hence are more favorable for the absorption in the visible-light region. In comparison with B- and N-doped TiO2, (B, N)-codoped TiO2 tends to exhibit a much higher visible-light photocatalytic activity for the oxidation of rhodamine B. Accordingly, a photochemical mechanism of the (B, N)-codoped TiO2 under visible-light irradiation is proposed.

Herein, an example of Cu-doped few-layer ZnIn 2 S 4 nanosheets is used to reveal the origin of optimum and excess doping for photocatalysts at atomic level. Results show that the metal-S 4 coordination maintains well with 0.5 wt% Cu substituted Zn atoms in the lattice. The introduced Cu atoms bring electronic acceptor states close to the valence band (VB) maximum and thus ensures higher charge density and efficient carrier transport, resulting in an optimum hydrogen evolution rate of 26.2 mmol h −1 g −1 and an apparent quantum efficiency of 4.76% at 420 nm. However, a distorted atomic structure and largely upshift of VB maximum with Cu-S 3.6 coordination are found with excess doping concentration (3.6 wt%). These bring the heavy charge recombination and consequentially dramatic reduced activity. This work provides a new insight into elemental doping study and takes an important step toward the development of ultrathin 2D photocatalysts.

Semiconductive property of elementary substance is an interesting and attractive phenomenon. We obtain a breakthrough that fibrous phase red phosphorus, a recent discovered modification of red phosphorus by Ruck et al., can work as a semiconductor photocatalyst for visible-light-driven hydrogen (H2 ) evolution. Small sized fibrous phosphorus is obtained by 1) loading it on photoinactive SiO2 fibers or by 2) smashing it ultrasonically. They display the steady hydrogen evolution rates of 633 μmol h(-1)  g(-1) and 684 μmol h(-1)  g(-1) , respectively. These values are much higher than previous amorphous P (0.6 μmol h(-1)  g(-1) ) and Hittorf P (1.6 μmol h(-1)  g(-1) ). Moreover, they are the highest records in the family of elemental photocatalysts to date. This discovery is helpful for further understanding the semiconductive property of elementary substance. It is also favorable for the development of elemental photocatalysts.

A new visible‐light responsive metallic photocatalyst, nanostructured MoO2, has been discovered. The metallic nature of MoO2 is confirmed by valance X‐ray photoelectron spectroscopy spectrum and theoretical calculations. However, MoO2 itself shows only moderate activity due to the serious charge recombination, a general disadvantage of metallic photocatalysts. The findings suggest that its effective charge diffusion length Lp is smaller than 1.0 nm while the separation efficiency ηsep is less than 10%. Therefore, only the periphery of the metallic MoO2 can effectively contribute to photocatalysis. This limitation is overcome by integrating MoO2 in a hydrothermal carbonation carbon (HTCC) matrix (mainly contains semiconductive polyfuran). This simple chemical modification brings two advantages: (i) an internal electric field is formed at the interface between MoO2 and HTCC due to their appropriate band alignment; (ii) the nanostructured MoO2 and the HTCC matrix are intertwined with each other intimately. Their small size and large contact area promote charge transfer, especially under the internal electric field. Therefore, the separation rate of photoexcited charge carrier in MoO2 is greatly enhanced. The activity increases by 2.4, 16.8, and 4.0 times in photocatalytic oxygen evolution, dyes degradation, and photoelectrochemicl cell, respectively. The new approach is helpful for further development of metallic photocatalysts.