Non-Metal Sulfur Doping of Indium Hydroxide Nanocube for Selectively Photocatalytic Reduction of CO2 to CH4: A "One Stone Three Birds" Strategy.

Photocatalytic CO2 reduction is considered as a promising strategy for CO2 utilization and producing renewable energy, however, it remains challenge in the improvement of photocatalytic performance for wide-band-gap photocatalyst with controllable product selectivity. Herein, the sulfur-doped In(OH)3 (In(OH)xSy-z) nanocubes are developed for selective photocatalytic reduction of CO2 to CH4 under simulated light irradiation. The CH4 yield of the optimal In(OH)xSy-1.0 can be enhanced up to 39 times and the CH4 selectivity can be regulated as high as 80.75% compared to that of pristine In(OH)3. The substitution of sulfur atoms for hydroxyl groups in In(OH)3 enhances the visible light absorption capability, and further improves the hydrophilicity behavior, which promotes the H2O dissociation into protons (H*) and accelerates the dynamic proton-feeding CO2 hydrogenation. In situ DRIFTs and DFT calculation confirm that the non-metal sulfur sites significantly weaken the over-potential of the H2O oxidation and prevent the formation of ·OH radicals, enabling the stabilization of *CHO intermediates and thus facilitating CH4 production. This work highlights the promotion effect of the non-metal doping engineering on wide-band-gap photocatalysts for tailoring the product selectivity in photocatalytic CO2 reduction.

In situ electrochemical Mn vacancies in CoMnHCF for a high level of zinc storage.

CoMnHCF is utilized in aqueous sodium/zinc mixed ion batteries and exhibits a high reversible capacity with good rate and cycle performances. At 0.05 A g-1 current density, the CoMnHCF can deliver a specific capacity for 180.4 mA h g-1, and have 99.3% capacity retention after 300 cycles at 0.3 A g-1. Such high reversible capacity profits from Mn vacancies that generate in situ during the first cycle, which provides more active sites for Zn storage. The de-intercalation of Na+ further elevates this good electrochemical performance. Co atoms in the framework are not only involved in the redox reactions, but help to support the structure, thus achieving better cycle stabilities.

Ternary CdS@MoS2-Co3O4 Multiheterojunction Photocatalyst for Boosting Photocatalytic H2 Evolution.

Turning the carrier dynamics in heterojunction photocatalysts is a direct and effective strategy for improving the solar energy conversion efficiency of photocatalysts. Herein, we report a ternary CdS@MoS2-Co3O4 multiheterojunction photocatalyst consisting of the p-n junction of MoS2-Co3O4 and the type-I junction of CdS@MoS2, wherein MoS2 located at the frontier between CdS and Co3O4 acts as an intermediate bridge. The type-I junction allows the directional transfer of photoinduced charge from CdS to MoS2, suppressing the photocorrosion of CdS. Notably, the single-particle photoluminescence technique demonstrates the sequential one-direction hole transfer from MoS2 to Co3O4 aroused by the p-n junction, resulting in a long-lifetime charge separation in the carrier lifetime (54-58 ns). Compared to the bare CdS and type-I CdS@MoS2, the CdS@MoS2-Co3O4 photocatalyst affords a 347-fold and 3.5-fold enhancement of the H2 evolution rate, a quantum efficiency of 28.6% at 450 nm, and a 20 h of long-term stability. This work provides a new understanding of the rational regulation of the charge-transfer mechanism of type-I systems by constructing multiheterojunction photocatalysts.

Pine Dendritic Bi/BiOBr Photocatalyst for Efficient Degradation of Antibiotics.

Constructing Bi/BiOX (X = Cl, Br) heterostructures with unique electron transfer channels enables charge carriers to transfer unidirectionally at the metal/semiconductor junction and inhibits the backflow of photogenerated carriers. Herein, novel pine dendritic Bi/BiOX (X = Cl, Br) nanoassemblies with multiple electron transfer channels have been successfully synthesized with the assistance of l-cysteine (l-Cys) through a one-step solvothermal method. Such a pine dendritic Bi/BiOBr photocatalyst shows excellent activity toward the degradation of many antibiotics such as tetracycline (TC), norfloxacin, and ciprofloxacin. In particular, its photocatalytic degradation activity of TC is higher than those of reference spherical Bi/BiOBr, lamellar BiOBr, and BiOBr/Bi/BiOBr double-sided nanosheet arrays. Comprehensive characterizations demonstrate that the pine dendritic structure can construct multiple electron transfer channels from BiOBr to metallic Bi, resulting in an obviously promoted separation efficiency of photogenerated carriers. The synthesis method that uses l-Cys to control the morphology provides a guidance to prepare special metal/semiconductor photocatalysts and would be helpful to design a highly efficient photocatalytic process.

Excellent upconversion luminescence and temperature sensing performance of CdMoO4:Er3+,Yb3+ phosphors.

In this paper, Er3+/Yb3+ co-doped CdMoO4 phosphors were prepared by a traditional high temperature solid state reaction method. Based on the 3D network structure of the CdMoO4 host and the efficient Er3+/Yb3+ upconversion luminescence combinations, excellent green emission properties were observed when the prepared sample is irradiated with a laser at about 980 nm. For optical temperature sensors based on the fluorescence intensity ratio (FIR), the prepared phosphors have excellent sensitivity to temperature in the range of 293 to 473 K. With increasing environmental temperatures, the absolute sensitivity of the CdMoO4:0.02Er3+,0.08Yb3+ sample reached a maximum at about 473 K (Sa = 1.388% K-1). The calculated relative sensitivity of the optical temperature sensor was Sr = 1.631% K-1 at 293 K. This is due to the sensitive thermally coupled energy levels (TCLs) of the Er3+ ions (2H11/2 and 4S3/2) in the CdMoO4 structure. Therefore, it is shown that the prepared CdMoO4:0.02Er3+,0.08Yb3+ phosphor has excellent applications in non-contact optical temperature measurement.

An Open-Framework Structured Material: [Ni(en)2]3[Fe(CN)6]2 as a Cathode Material for Aqueous Sodium- and Potassium-Ion Batteries.

Open-framework structured materials such as Prussian blue analogues and sodium superionic conductor (NASICON) materials have been regarded as promising electrode candidates for aqueous batteries. These materials exhibit outstanding long cycle stability and high rate capacity retention, due to their high ion diffusive rate in the crystal and the stable structure maintenance in the electrochemical reaction process. Herein, an open-framework structured material [Ni(en)2]3[Fe(CN)6]2 (NienHCF) is prepared and first used as a cathode material for aqueous sodium- and potassium-ion batteries. The resultant material exhibits a high output potential and outstanding cycle performance (93.4% after 500 cycles at 1 A g-1) in K-ion batteries. Meanwhile, the electrochemical reaction mechanism is investigated. After coupling with the activated carbon anode, the K-ion full cell has 91.5% capacity retention at 5 A g-1 and retains 77.2% after 1000 cycles at 0.5 A g-1, exhibiting the potential as an electrode material for rechargeable aqueous K-ion and Na-ion batteries.

Bifunctional application of La3BWO9:Bi3+,Sm3+ phosphors with strong orange-red emission and sensitive temperature sensing properties.

Through a solid-phase reaction technique, Sm3+ and Bi3+ co-doped La3BWO9 phosphors with high emission intensity and sensitive temperature sensing properties have been successfully synthesized. Based on XRD Rietveld refinement, the optimized crystal structure was used as the original model to calculate the band structure and partial density of states (PDOS) by density functional theory (DFT) calculations. The luminescence characteristics of Sm3+ and Bi3+ co-doped La3BWO9 phosphors were measured and analyzed. In addition, the optimal doping concentrations of Sm3+ and Bi3+ were investigated. The luminescence properties of Sm3+ doped phosphors were optimized by introducing Bi3+ ions. Efficient energy transfer from Bi3+ to Sm3+ ions was observed in La3BWO9:Sm3+, Bi3+ phosphors. An optical temperature sensor with high sensitivity was designed based on the different thermal quenching properties of Sm3+ and Bi3+ ions. In the temperature range of 293-498 K, the optimum absolute sensitivity (Sa) and maximum relative sensitivity (Sr) were 2.88 %K-1 and 1.32 %K-1, respectively. These results indicated that the prepared La3BWO9:Bi3+, Sm3+ phosphors have wide application prospects as solid state lighting materials and optical temperature sensors.

Synthesis of Molecular Imprinted BiVO4 with Enhanced Adsorption and Photocatalytic Properties Towards Target Contaminants.

Selective photocatalysis is a very promising direction to improve the activities of photocatalysts. Combining the technique of molecular imprinting (MIP) with heterogeneous photocatalysis can be an appealing approach to achieve our aim. Herein, using the MIP technique, the monoclinic MIP-BiVO4 was successfully synthesized by the presence of rhodamine B (RhB) during the hydrothermal synthesis. The synthesized MIP-BiVO4 possessed better adsorptive and photocatalytic activities than pristine BiVO4. RhB added in the synthesis process worked as a template and served a crucial role in the formation of the MIP-BiVO4 morphology. The photoelectrochemical analysis verified the superiority of MIP-BiVO4 sample in the transfer and separation of the electron-hole pairs. Holes played the most crucial role in the degradation of the pollutants. The effective approach combining MIP technique in the synthesis of photocatalysts would provide some guidance to selective photocatalysis field for designing and synthesizing highly efficient photocatalysts.

Enhanced CO2 Photocatalysis by Indium Oxide Hydroxide Supported on TiN@TiO2 Nanotubes.

Herein is developed a ternary heterostructured catalyst, based on a periodic array of 1D TiN nanotubes, with a TiO2 nanoparticulate intermediate layer and a In2O3-x(OH)y nanoparticulate shell for improved performance in the photocatalytic reverse water gas shift reaction. It is demonstrated that the ordering of the three components in the heterostructure sensitively determine its activity in CO2 photocatalysis. Specifically, TiN nanotubes not only provide a photothermal driving force for the photocatalytic reaction, owing to their strong optical absorption properties, but they also serve as a crucial scaffold for minimizing the required quantity of In2O3-x(OH)y nanoparticles, leading to an enhanced CO production rate. Simultaneously, the TiO2 nanoparticle layer supplies photogenerated electrons and holes that are transferred to active sites on In2O3-x(OH)y nanoparticles and participate in the reactions occurring at the catalyst surface.

Bismuth atom tailoring of indium oxide surface frustrated Lewis pairs boosts heterogeneous CO2 photocatalytic hydrogenation.

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H2 and CO2 molecules and enable efficient gas-phase CO2 photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In3+ ions in In2O3 by single-site Bi3+ ions, thereby enhancing the propensity to activate CO2 molecules. The so-formed BixIn2-xO3 materials prove to be three orders of magnitude more photoactive for the reverse water gas shift reaction than In2O3 itself, while also exhibiting notable photoactivity towards methanol production. The increased solar absorption efficiency and efficient charge-separation and transfer of BixIn2-xO3 also contribute to the improved photocatalytic performance. These traits exemplify the opportunities that exist for atom-scale engineering in heterogeneous CO2 photocatalysis, another step towards the vision of the solar CO2 refinery.

Plasmonic Titanium Nitride Facilitates Indium Oxide CO2 Photocatalysis.

Nanoscale titanium nitride TiN is a metallic material that can effectively harvest sunlight over a broad spectral range and produce high local temperatures via the photothermal effect. Nanoscale indium oxide-hydroxide, In2 O3- x (OH)y , is a semiconducting material capable of photocatalyzing the hydrogenation of gaseous CO2 ; however, its wide electronic bandgap limits its absorption of photons to the ultraviolet region of the solar spectrum. Herein, the benefits of both nanomaterials in a ternary heterostructure: TiN@TiO2 @In2 O3- x (OH)y are combined. This heterostructured material synergistically couples the metallic TiN and semiconducting In2 O3- x (OH)y phases via an interfacial semiconducting TiO2 layer, allowing it to drive the light-assisted reverse water gas shift reaction at a conversion rate greatly surpassing that of its individual components or any binary combinations thereof.

Black indium oxide a photothermal CO2 hydrogenation catalyst.

Nanostructured forms of stoichiometric In2O3 are proving to be efficacious catalysts for the gas-phase hydrogenation of CO2. These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In2O3 has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In2O3 to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In2O3-x on a core of crystalline stoichiometric In2O3, and has 100% selectivity towards the hydrogenation of CO2 to CO with a turnover frequency of 2.44 s-1.

Living Atomically Dispersed Cu Ultrathin TiO2 Nanosheet CO2 Reduction Photocatalyst.

Supported atomically dispersed metals are proving to be efficacious photocatalysts for CO2 reduction to solar fuels. While being atom efficient, they suffer from being noble, rare, and costly (Pt, Pd, Au, Ag, Rh) and lacking in long-term stability. Herein, all of these problems are solved with the discovery that atomically dispersed Cu supported on ultrathin TiO2 nanosheets can photocatalytically reduce an aqueous solution of CO2 to CO. The atomically dispersed Cu can be recycled in a straightforward procedure when they become oxidatively deactivated. This advance bodes well for the development of a solar fuels technology founded on abundant, low-cost, nontoxic, atomically dispersed metal photocatalysts.

Building a Bridge from Papermaking to Solar Fuels.

Black liquor, an industrial waste product of papermaking, is primarily used as a low-grade combustible energy source. Despite its high lignin content, the potential utility of black liquor as a feedstock in products manufacturing, remains to be exploited. Demonstrated here in is the use of black liquor as a primary feed-stock for synthesizing graphene quantum dots that exhibit both up-conversion and photoluminescence when excited using visible/near-infrared radiation, thereby enabling the photosensitization of ultraviolet-absorbing TiO2 nanosheets. In addition, these graphene quantum dots can trap photo-generated electrons to realize the effective separation of electron-hole pairs. Together, these two processes facilitate the solar-powered generation of H2 from H2 O, and CO from H2 O-CO2 , using broadband solar radiation.

Polymorph selection towards photocatalytic gaseous CO2 hydrogenation.

Titanium dioxide is the only known material that can enable gas-phase CO2 photocatalysis in its anatase and rutile polymorphic forms. Materials engineering of polymorphism provides a useful strategy for optimizing the performance metrics of a photocatalyst. In this paper, it is shown that the less well known rhombohedral polymorph of indium sesquioxide, like its well-documented cubic polymorph, is a CO2 hydrogenation photocatalyst for the production of CH3OH and CO. Significantly, the rhombohedral polymorph exhibits higher activity, superior stability and improved selectivity towards CH3OH over CO. These gains in catalyst performance originate in the enhanced acidity and basicity of surface frustrated Lewis pairs in the rhombohedral form.

Room-Temperature Activation of H2 by a Surface Frustrated Lewis Pair.

Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas-phase heterogeneous (photo)catalytic hydrogenation of CO2 to CO and CH3 OH by In2 O3-x (OH)y . A key step in the reaction pathway is envisioned to be the heterolysis of H2 on a proximal Lewis acid-Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In-OH + H2 → In-OH2 + ⋅⋅⋅In-H- . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In-OH2 + and a hydride coordinated Lewis acid In-H- , can react with CO2 to form either CO or CH3 OH. While the experimental and theoretical evidence is compelling for heterolysis of H2 on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In2 O3-x (OH)y can enable dissociation of H2 at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.

The Multiple Promotion Effects of Ammonium Phosphate-Modified Ag3PO4 on Photocatalytic Performance.

Phosphate ( PO 4 3 - ) modification of semiconductor photocatalysts such as TiO2, C3N4, BiVO4, and etc. has been shown positive effect on the enhancement of photocatalytic performance. In the present study, we demonstrate a novel one-pot surface modification route on Ag3PO4 photocatalyst by ammonium phosphate [(NH4)3PO4], which combines PO 4 3 - modification with ammonium ( NH 4 + ) etching to show multiple effects on the structural variation of Ag3PO4 samples. The modified Ag3PO4 photocatalysts exhibit much higher photocatalytic performance than bare Ag3PO4 for the degradation of organic dye solutions under visible light irradiation. It is indicated that the NH 4 + etching favors the surface transition from Ag3PO4 to metallic Ag nanoparticles, resulting in the fast capture of photogenerated electrons and the followed generation of O 2 · - radicals. The strongly adsorbed PO 4 3 - on the Ag3PO4 surfaces can further provide more negative electrostatic field, which improves the separation of photogenerated electron-hole pairs by inducing the holes to directly flow to the surface and then enhances the formation of reactive ·OH radicals. Furthermore, the photocatalytic performance of the modified Ag3PO4 photocatalysts can be optimized by monitoring the concentration of (NH4)3PO4 that is 1 mM.

A new five-coordinated copper compound for efficient degradation of methyl orange and Congo red in the absence of UV-visible radiation.

A new copper-based coordination compound Cu2(2,2'-bipy)2(pfbz)4 (1) (where 2,2'-bipy = 2,2'-bipyridine; pfbz = pentafluorobenzoate), was hydrothermally synthesized and structurally characterized. Compound 1 having a binuclear structure consists of two copper cations and two oxygen atoms alternately in a plane square arrangement. In the presence of very small amounts of H2O2, the catalytic properties of compound 1 for the degradation of methyl orange (MO) are excellent in the absence of UV-visible radiation. Moreover, compound 1 presents suitable properties for degradation of Congo red (CR). Our results indicated that the five-coordinated copper compound, 1, will be a promising candidate for efficient degradation of organic dyes.

Relationship between surface hydroxyl groups and liquid-phase photocatalytic activity of titanium dioxide.

Both theories and experiments show that surface hydroxyl radicals (OH) are the most important intermediate species in the photocatalytic process. As a source of OH, surface hydroxyl (OH) groups play an important role in its generation. In this paper, the OH groups were divided into surface acidic hydroxyl (OH(a)) and surface basic hydroxyl (OH(b)) groups. From the detection by a method of surface acid-base, ion-exchange reactions, the total surface density of OH groups was about 9.58×10(-5) mol m(-2). The results measured by Fourier transform infrared spectroscopy, (1)H magnetic-angle spinning NMR and electron spin resonance techniques demonstrated that the role of OH(a) groups was greater than that of OH(b) groups on the generation of OH radicals. By degradation of methyl orange, rhodamine B and p-chlorophenol, the photocatalytic activities of the catalysts were directly influenced by the amount of OH groups.

Porous SnIn4S8 microspheres in a new polymorph that promotes dyes degradation under visible light irradiation.

Porous SnIn(4)S(8) microspheres were initially synthesized through a facile solvothermal approach and were investigated as visible-light driven photocatalysts for dyes degradation in polluted water. The photocatalysts were characterized by XRD, SEM, TEM, N(2) adsorption-desorption, and UV-vis diffuse reflectance techniques. Results demonstrated that the as-synthesized SnIn(4)S(8) was of a new tetragonal polymorph, showing a band-gap of 2.5 eV, a specific surface area of 197 m(2) g(-1), and an accessible porous structure as well. The photocatalytic activity of the porous SnIn(4)S(8) was evaluated by decomposition of several typical organic dyes including methyl orange, rhodamine B, and methylene blue in aqueous solution under visible light irradiation. It is demonstrated that porous SnIn(4)S(8) was highly photoactive and stable for dyes degradation, showing photocatalytic activity much higher than binary constituent sulfides like In(2)S(3), SnS(2), or even ternary chalcogenide ZnIn(2)S(4) photocatalyst. The excellent photocatalytic performance of porous SnIn(4)S(8) is the consequence of its high surface area, well-defined porous texture, and large amount of hydroxyl radicals.