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Porphyrin is an important photosensitizer for singlet oxygen (1O2) formation. However, porphyrin derivatives still display low efficiency and difficult recovery. In this work, an Ag-based MOFs (AgTPyP; TPyP, 5,10,15,20-tetra(4-pyridyl) porphyrin) is synthesized. Compared with ligand TPyP, AgTPyP shows nearly 100% conversion and selectivity in the photocatalytic selective oxidation of sulfides to sulfoxides and obvious photodynamic therapeutic effect under visible light. Combined characterizations suggest that 1O2 is the only active oxygen species, which is due to the large exciton binding energy and narrow energy gap between the lowest excited singlet state (S1) and the lowest triplet state (T1) induced by the presence of Ag+ ion. The selectivity and conversion efficiency of five-cycle experiments do not decrease, indicating the excellent stability of AgTPyP. This work provides an alternative approach to simultaneously enhance the exciton effect of porphyrin and stabilize Ag-based photocatalysts.

Hydrogenation of nitroaromatics is typically performed under harsh reaction conditions, which would bring safety issues and energy waste. The key for the hydrogenation reaction is to finely control...

For traditional cycloaddition reaction between CO2 and epoxide, high temperature and high pressure are usually needed. In this work, we introduce Lewis acid Bi atom into the porphyrin ring of a met...

Ni/TiO2 as a classic system has been widely studied in the traditional catalysis field including the water-gas shift reaction and selective oxidation/hydrogenation. However, in terms of the electrocatalytic hydrogen evolution reaction (HER), there is still a lack of systematic research on the actual synergistic promotion effect on the performance, and the influence of the host material on the electronic interaction between Ni and TiO2 is still unclear. Herein, we synthesized a series of Ni/TiO2 composites with different forms and tested the relevant HER performance. The results show that Ni/TiO2 exhibits much better HER performance than pure Ni and there is one type of electronic interaction between Ni and TiO2 in the composite with different forms, that is, electrons transfer from Ni to TiO2. However, the interaction strength is host dependent, and the composite with Ni as the host displays the strongest interaction, and therefore the best HER performance (46 mV at 10 mA cm−2).

Photocatalytic H2 generation has been believed to be a hopeful technology to deal with the current energy shortage issue. Among multifarious photocatalysts, graphitic carbon nitride (g-C3N4) has acquired enormous interests in virtue of its numerous advantages, such as peculiar physicochemical stability, favorable energy band structure and easy preparation. However, the insufficient light response range, low specific surface area, and inferior charge separation efficiency make its photocatalytic activity still unsatisfactory. In this work, the thermal exfoliation method was taken to prepare the thin g-C3N4 nanosheets with significantly improved specific surface area, which can afford more reaction sites and shorten the charge migration distance. Moreover, phosphorus (P) doping in g-C3N4 nanosheets can greatly expand its light absorption, improve the conductivity and charge-transfer capability. Due to the synergistic effect of these two strategies, the optimal H2 generation performance of P-doped g-C3N4 nanosheets came up to 1146.8 μmol g−1 h−1, which improved 15, 2.94 and 2.62 times compared to those of original bulk g-C3N4, thermally exfoliated g-C3N4 and P-doped bulk g-C3N4, respectively. The synergistic effect will inspire the design of other photocatalytic systems to achieve the efficient photocatalytic H2 generation activity.

The rate-determining step of the photoelectrochemical (PEC) water splitting is the water oxidation reaction at the photoanode, which is 4 orders of magnitude slower than the water reduction reactio...

In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and AuAg alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the AuAg alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance (SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in AuAg/ZnO. Therefore, the cooperative action of plasmonic AuAg bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains AuAg/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.

Loss-in-capacity of carbide slag in CO2 capture restricts the development of industrial wastes in calcium looping technology. In this work, a novel Mn/Mg-copromoted carbide slag was prepared using carbide slag, dolomite and trace Mn(NO3)2 additive. Experimental tests were carried out in the fixed-bed reactor to evaluate how the preparation and the reaction conditions influenced the CO2 capture performance of Mn/Mg-copromoted carbide slag during calcination/carbonation cycles. Results show that MgO diminishes the sintering of synthetic sorbents. The optimal Mn/Mg-copromoted carbide slag (mass ratio of CaO:MgO:MnO2 = 89:10:1) exhibits the highest CO2 capture capacity of 0.52 g/g after 10 cycles under the severe calcination condition (100 % CO2, 950 °C) and the wet carbonation condition (15 % CO2/20 % steam/N2), which is 1.7 times as high as that of untreated carbide slag. MnO2 positively affects the slow carbonation stage by enhancing the electron transfer between CaO and CO2. Observations of the morphology of Mn/Mg-copromoted carbide slag indicate that the stabilized CO2 capture performance is mainly attributed to porous structure, MgO as the skeleton and MnO2 as an electron-transfer promoter.

Oxygen vacancies are usually thought to be beneficial for photogenerated charge separation. In this work, the oxygen vacancies in ov-Bi2 O3 (Bi2 O3 with oxygen vacancy) were found to be able to produce 1 O2 in the dark owing to chemical adsorption. The oxygen vacancies were further found to be responsible for ov-Bi2 O3 exhibiting higher 1 O2 generation under light irradiation with 1 O2 as the only reactive oxygen species (ROS) than Bi2 O3 with 1 O2 , H2 O2 , and others as the ROS. The photocatalytic activity was investigated for the selective photo-oxidation of phenyl methyl sulfide to phenyl methyl sulfoxide and phenyl alcohol to benzaldehyde. In either case, ov-Bi2 O3 displayed better performance than Bi2 O3 , suggesting the significant role of oxygen vacancies in modulating the photocatalytic oxidation properties. This work provides an alternative approach to obtain singlet oxygen, which may guide further design of photocatalysts with high efficiency and selectivity towards photocatalytic organic synthesis.

In this work, the SO2 removal performances of the aluminum- and the magnesium-modified carbide slags fabricated by the combustion synthesis from CO2 capture cycles at the calcium looping conditions were investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The effects of sulfation temperature, number of CO2 capture cycles and calcination condition on the SO2 removal performances of Al- and Mg-modified carbide slags experienced the multiple CO2 capture cycles were studied. The sulfation temperature in the range of 800–950 °C shows a little effect on SO2 removal capacities of Al- and Mg-modified carbide slags experienced the multiple CO2 capture cycles. As the number of CO2 capture cycles increases, the sulfation conversions of the original and modified carbide slags decrease rapidly. However, Al- and Mg-modified carbide slags possess obviously higher SO2 removal capacity and cyclic stability than original carbide slag due to the good supports Ca3Al2O6 and MgO, respectively. And the larger surface areas and volumes of pores in 5–20 nm in diameter of Al- and Mg-modified carbide slags promote the higher SO2 removal capacity than original carbide slag. The modified carbide slag shows higher sintering resistance in high concentration of steam calcination condition during the CO2 capture cycles, compared with high concentration of CO2 calcination condition. Therefore, Al- and Mg-modified carbide slags from CO2 capture cycles based on calcium looping calcined under high steam concentration achieve SO2 removal capacities.

The oxygen evolution reaction (OER) plays a vital role in various energy conversion applications. Up to now, the highly efficient OER catalysts are mostly based on noble metals, such as Ir- and Ru-based catalysts. Thus, it is extremely urgent to explore the non-precious electrocatalysts with great OER performance. Herein, a simple electrodeposition combined with hydrothermal method is applied to synthesize a non-precious OER catalyst with a three-dimensional (3D) core-shell like structure and excellent OER performance. In our work, NiFe layered double hydroxide (LDH) was electrodeposited on Ni3S2 nanosheets on nickel foam (NF), which exhibits a better performance compared with RuO2, and a low overpotential of 200 mV is needed to reach the current density of 10 mA/cm2 in 1 M KOH. Notably, the Ni3S2/NiFe LDH only need an overpotential of 273 mV to reach the current density of 200 mA/cm2.

In this work, a simultaneous SO2/NO removal method using pellets made of carbide slag and coal char by extrusion-spheronization process was proposed. The effects of char type, reaction temperature, O2 concentration, initial NO/SO2 concentration and the addition of supporters on the simultaneous SO2/NO removal performance of the pellets made of carbide slag and coal char were investigated in a bubbling fluidized-bed reactor. CaO derived from carbide slag not only acts as an excellent desulfurizer but also catalyzes the reduction of NO by coal char. The results show that the pellets made of carbide slag and coal char possess better simultaneous SO2/NO removal performance than the pellets made of carbide slag and bio-char. The optimal reaction temperature range for SO2/NO removal by the pellets made of carbide slag and coal char is 850−875 °C. The addition of the supporters such as Al2O3 and high alumina cement enhances the mechanical strength of the pellets. The pellets made of carbide slag and coal char seems promising for efficient simultaneous SO2/NO removal in the circulating fluidized bed decoupling combustion.

In this paper, we focus on the three-block nonconvex optimization problem of background/foreground extraction from a blurred and noisy surveillance video. The coefficient matrices of the equality constraints are nonidentity matrices. Regarding the separable structure of the objective function and linear constraints, a benchmark solver for the problem is the alternating direction method of multipliers (ADMM). The computational challenge is that there is no closed-form solution to the subproblem of ADMM since the objective function is not differentiable and the coefficient matrices of the equality constraints are not identity matrices. In this paper, we propose a linearized ADMM by choosing the proximal terms appropriately and add the dual step size to make the proposed algorithm more flexible. Under proper assumptions and the associated function satisfying the Kurdyka-Łojasiewicz property, we show that the proposed algorithm converges to a critical point of the given problem. We apply the proposed algorithm to the background/foreground extraction and the numerical results are used to demonstrate the effectiveness of the proposed algorithm.

Developing a simple and general method to fabricate graphitic carbon nitride (g-CN) film is crucial for the application of devices. Herein, we report a CCl4-assisted method for the fabrication of continuous g-CN films on various substrates with in-situ extracted metal cations as nucleate sites. The g-CN film exhibits continuous wrinkles-like graphene structure, and can be completely exfoliated as a free-standing film. In the g-CN film, the metallic cations are bonded with the electron-rich nitrogen as the nucleate sites for connecting molecular structure. By changing the synthesis temperature and the flow rate of CCl4, the thickness and the band structure of the g-CN films can be successfully adjusted. Under visible light illumination, the g-CN films exhibit efficient hydrogen evolution with a rate of 74.98 μmol g−1 h−1. We believe that the precise controlled free-standing g-CN film will shed light on many opportunities in the utilization of graphitic carbon nitride for catalysis, sensor, electronic and energy-related applications. This method may open a new avenue to fabricate other two-dimensional films on different substrates.

Graphitic carbon nitride tetragonal hollow prism (GCN-THP) with nitrogen vacancies was prepared by a simple two-step calcination method. Based on the characterizations of the as-prepared GCN-THP and the intermediate precursor, a possible mechanism was proposed for the formation of GCN-THP. The as-prepared GCN-THP exhibits superior activity and excellent stability during photocatalytic hydrogen evolution under visible light irradiation. The photocatalytic hydrogen evolution rate of GCN-THP was measured to be 1990 μmol g−1 h−1, which is 6.2 times as that of GCN. The enhanced photocatalytic activity could be attributed to unique 1D tetragonal hollow prism morphology and the presence of nitrogen vacancies in the as-prepared GCN-THP, which could increase the surface area, expand the visible light absorption, and promote the charge separation during photocatalytic hydrogen evolution. Our work could provide a new route to synthesize highly efficient photocatalysts with 1D hollow structures.

So far, most efforts in photocatalysis have been devoted to the separation of photogenerated electron-hole pairs, and possible use of excitons (i.e., electron-hole pairs) for photocatalytic processes has not received much attention. In this work, we studied the effect of metal dots on the excitonic behaviors of two bismuth-based MOFs, Bi-TATB and Bi-BTC (here the tridentate ligands TATB3− and BTC3− represent the carboxylates of 4,4′,4′'-s-triazine-2,4,6-triyl-tribenzoic and 1,3,5-benzenetricarboxylic acids, respectively). The organic ligands (TATB and BTC) display different emission properties from the corresponding Bi based MOFs. Specifically, TATB and BTC display strong fluorescence emission while Bi-TATB and Bi-BTC display strong phosphorescence emission, suggesting the higher efficiency of intersystem crossing for Bi-TATB and Bi-BTC. The reason is attributed to the coordination with Bi, which promotes the singlet→ triplet intersystem crossing of the organic ligand due to the heavy metal effect. The enhanced triplet excited emission of Bi-TATB and Bi-BTC was further confirmed by the detection of 1O2, as 1O2 is well known to be formed due to energy transfer from the triplet state of photosensitizers to the ground-state oxygen (3O2). With above understanding, Bi-TATB and Bi-BTC were finally used to high selective photooxidation of benzyl alcohol to benzaldehyde. This work presents new understanding of the photophysical properties of Bi based MOFs, which provides alternative ideas on designing materials for selective photo-oxidation.

UiO-67 is a Zr-based metal–organic framework (MOF) containing an organic linker namely, the dianion of biphenyl-4,4′-dicarboxylic acid (bpdc). Ce4+ metal ions (0.02 Ce to Zr atom ratio) were incorporated into UiO-67 via partially replacing bpdc with the dianion of 2,2′-bipyridine-5,5′-dicarboxylic acid (bpydc); thus, the latter forms a bpydc-Ce complex. The resulting product (i.e., UiO-67-Ce) demonstrated a photocatalytic hydrogen evolution rate that was over 10 times higher than that of UiO-67. Through this modification, a new energy transfer channel is opened up. The energy transfer between the bpdc and bpydc-Ce ligands (i.e., from excited bpdc to bpydc-Ce) weakened the recombination of the charge carriers, which was confirmed by photoluminescence, emission lifetime, and transient absorption measurements. This study presents a new way to construct highly efficient MOF photocatalysts.

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.

The synthetic CaO/Ca12Al14O33 sorbent has been regarded as an efficient CO2 sorbent during the calcium looping cycles. In this work, the CO2 adsorption performance of the synthetic CaO/Ca12Al14O33 sorbent in the presence of H2O was investigated by density functional theory (DFT) calculations. DFT was used to analyze the adsorption of CO2 and H2O on the synthetic sorbent. Both structural parameters (atomic layout and electronic configuration) and the adsorption parameters (energy, bond lengths, angles, bond population and charge transfer) of CO2 and H2O on the synthetic sorbent were determined. To confirm the feasibility of DFT analysis, the CO2 capture performance of the synthetic sorbent in the presence of steam was examined in a dual fixed bed reactor. The results indicate strong interactions between the C atom and the O atom in CaO and interactions between the H atom and the O atom in CaO. The higher adsorption energy of CO2 than H2O on pristine CaO and Ca12Al14O33-supported CaO suggests that the adsorptions of CO2 and H2O are competitive and that the adsorption of CO2 is stronger than that of H2O. The adsorption of H2O leads to the activation of adjacent O atoms of CaO and thus stronger CO2 adsorption on the O atom with H2O adsorbed. The electrons in the p orbital of the O atom near the Fermi level play important roles in CO2 adsorption by CaO. The presence of Ca12Al14O33 hinders CO2 adsorption by CaO. A low Ca12Al14O33 content in synthetic sorbents should be maintained to ensure high CO2 capture capacity and sintering resistance of synthetic sorbents. DFT calculations can predict the CO2 adsorption performance of CaO-based sorbents with additives under different reaction atmospheres.

Tetragonal zircon BiVO4 (P-BiVO4) were grown on fluorine-doped tin oxide (FTO) glass via hydrothermal method. The cathodic photocurrent and Mott-Schottky analysis indicate that the tetragonal zircon BiVO4 is a p-type semiconductor. Inductively coupled plasma (ICP) analysis and X-ray photoelectron spectrum showed that there are Bi vacancies and interstitial oxygen exist in the crystal, which are the origin of the p-type conductivity. The flat band potential of the P-BiVO4 is about 1.33 V (vs Ag/AgCl) inferred from Mott-Schottky plots. Combining with diffuse reflection spectrum and valence band X-ray photoelectron spectrum, the calculated conduction band value of the P-BiVO4 is about 0.06 V vs RHE, slightly higher than the reduction potential of hydrogen. However, the P-BiVO4 exhibit hydrogen production activity under Xe light irradiation even though its conduction band level is not negative enough. This can be attributed to the hot carrier processes in p-type semiconductors.

In this work, we provide an alternative way to modulate the type of major reactive oxygen species produced during the photocatalytic process. Polar molecular 4-carboxythiophenolate anion (4CBT) mod...

Enhancing the photocatalytic activity of NiO towards hydrogen generation (6 times) is achieved by phenyl phosphoric acid (PPA) surface modification. The photocatalytic activity can be further improved by changing PPA to 4-aminophenyl phosphonic acid (PPA-NH2), about 10 times, suggesting the functional group plays an important role in improving the activity. A chemical bond (Ni O P) between NiO and organic phosphoric acid was proved by FT-IR spectra. XPS and LSV analysis suggested organic phosphonic acid modification increased the electron density of Ni, which promoted the transformation from Ni2+ to Ni0. Mott-Schottky (M − S) measurement revealed that PPA-NH2 modified NiO processed a larger the space charge layer thickness (dsc), which enhanced ability towards H2 evolution from dynamical aspect.

A simple and efficient light-assisted method is employed to prepare powder samples of all-inorganic mixed-perovskite CsPbBr3-xIx from CsPbBr3 by ion exchange in aqueous HBr/KI solution such that the concentration of I in a sample particle decreases on going from the surface to the interior. CsPbBr3-xIx/Pt, namely, CsPbBr3-xIx samples loaded with Pt nanoparticles, shows a high performance for the hydrogen evolution under visible-light irradiation in aqueous HBr solution saturated with CsPbBr3. The H2 evolution rate of the CsPbBr3-xIx/Pt powders (200 mg) is determined to be 224 μmol h−1, under 120 mW cm-2 visible-light (λ ≥ 420 nm) illumination. The CsPbBr3-xIx samples have a high stability, with no apparent decrease in the catalytic activity after 50 h of repeated H2 evolution experiments. The apparent quantum efficiency of CsPbBr3-xIx/Pt is determined to be 2.15% under the irradiation of 450 nm light.

Calcium looping is regarded as an effective and viable way to address CO2 emissions. To overcome the loss-in-capacity problems of calcium-based sorbents with the number of calcium looping cycles, a novel CaO/Ca12Al14O33 sorbent with a microtube-like structure was prepared from carbide slag and Al(NO3)3·9H2O using paper fibre as a biotemplate. The CO2 capture performance and microstructure of the novel synthetic sorbent under calcium looping conditions were investigated. The results show that the utilization of the biotemplate is good to retain the high cyclic CO2 capture reactivity of the synthetic sorbent. Due to the unique hollow porous structure, the CO2 capture capacity of the synthetic sorbent containing 7.5 wt% Al2O3 retains 0.56 and 0.33 g/g after 30 cycles under mild and severe calcination conditions, respectively, which are 2.56 and 2.11 times higher than those of carbide slag under the same respective calcination conditions. With the presence of 10% steam in the carbonation atmosphere, the CO2 capture capacity of the synthetic sorbent retains 0.55 g/g under the severe calcination conditions after 10 cycles. The native hierarchical biostructure of paper fibre is preserved in the synthetic sorbent. CaO and Ca12Al14O33 are uniformly distributed in the synthetic sorbent, resulting in a high sintering resistance during multiple CO2 capture cycles. CO2 can penetrate through the microtube-like structure of the synthetic sorbent from two directions, i.e., from the outer surface and inner surface. This phenomenon effectively enlarges the contact area between CO2 and CaO. The CaO/Ca12Al14O33 sorbent with a hollow porous structure by means of a biotemplate appears promising in the calcium looping technology for CO2 capture.

In this work, we fabricated NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+@TiO2 (Tm@Nd@TiO2) core@shell nanoparticles and investigated their near-infrared (NIR) photocatalytic activities. Comparing to traditional TiO2 based upconversion (UC) photocatalysts (i.e., NaYF4:Yb3+,Tm3+@TiO2, named Tm@TiO2), Tm@Nd@TiO2 exhibits enhanced photocatalytic activity under NIR light irradiation. The photocatalytic activity of Tm@Nd@TiO2 under 980, 808, and 980 + 808 nm laser irradiation is 4.40, 5.84, and 9.83 times as high as that of Tm@TiO2 under only 980 nm irradiation, respectively. The ethylene degradation rate of Tm@Nd@TiO2 under 980 + 808 nm laser irradiation is 6.4 times as that of Tm@TiO2. The photocatalytic activity of Tm@Nd@TiO2 under visible + NIR irradiation is even comparable with (∼2/3) that under UV light irradiation during Rhodamine B (RhB) degradation. The enhanced photocatalytic activity of Tm@Nd@TiO2 can be attributed to the stronger light absorption in NIR region ascribed to Nd3+, lower water absorption and the enhanced UC emission of Tm@Nd with unique core@shell nanostructures. This work can provide a possible route to improve the NIR photocatalytic activity and stimulate the applications in many other fields.

Interfacial manipulation of nanostructured heterojunction photocatalysts to enhance charge separation and transfer is highly desirable to achieve a high photocatalytic activity. In this work, a well-designed non-noble-metal Mo2C@C/g-C3N4 heterostructure is constructed, in which the intercalated carbon nanosheets serve as a binder to form an excellent interfacial contact between Mo2C and g-C3N4. In addition, large quantities of carbon quantum dotsare found to be homogeneously embedded in the carbon nanosheets. The as-obtained Mo2C@C/g-C3N4 hybrid exhibits a remarkably improved photocatalytic H2 evolution rate of 52.1 μmol h−1 under visible-light irradiation (λ ≥ 420 nm) without co-catalyst, which is up to nearly 260 times higher than that of pristine g-C3N4 (0.2 μmol h−1) under the same conditions. The significant increase in photocatalytic activity mainly results from the fast charge migration and separation between Mo2C and g-C3N4 facilitated by the conducting carbon nanosheets as an efficient electron mediator. Moreover, the carbon quantum dots embedded in the carbon support also promotes solar energy utilization. This work highlights a feasible strategy to explore highly efficient photocatalysts via interfacial engineering on heterojunction composites.

Layered perovskite oxyhalide Bi4NbO8Cl with exposed (001) lattice plane has been successfully synthesized by Sol–gel method. The obtained products were characterized by X-ray diffraction, diffuse-reflection spectra, scanning electron surface area from Brunauer–Emmitt–Teller analysis. The photocatalytic activity for the decomposition of Rhodamine-B (RhB) aqueous solution can be significantly improved under visible light irradiation. Based on both high charge speration efficiency originated from the large exposed surface areas of (001) facts and high photocatalytic redox ability generated from band gap expansion, sol gel-Bi4NbO8Cl exhibit higher efficiency over solid state-Bi4NbO8Cl during the degradation of organic dyes under visble light irradiation. What’s more, the Sg-Bi4NbO8Cl photocatalyst still kept higher photocatalytic activity after five cycle measurement.

Novel Mn‐doped CaO was prepared by the combustion method. The CO2 capture performance of Mn‐doped CaO, carbonated in the presence of steam and under severe calcination conditions (950°C and 70% CO2/30% N2) during calcium looping cycles, was investigated in a dual fixed‐bed reactor. The intercoupling effects of Mn and steam on CO2 capture by CaO were also studied. Doping of Mn in CaO by the combustion method greatly improved the CO2 capture capacity of CaO. The carbonation conversions of Mn‐doped CaO increased with increasing steam concentration from 0 to 15%. When the molar ratio of Mn/Ca was 0.75 : 100, Mn‐doped CaO achieved the highest CO2 capture capacity. Under severe calcination conditions, the carbonation conversion of Mn‐doped CaO, where the molar ratio of Mn to Ca = 0.75 : 100 in the presence of 15% steam, was about 0.4 after ten cycles (carbonation for 5 min at 650°C under 15% CO2/15% steam/N2), which was 4.38 times as high as that of the original CaO in the absence of steam. The cyclic CO2 capture capacities of CaO were improved by Mn and steam. Synergistic enhancement effects of Mn and steam on the CO2 capture capacities of CaO were also found. The effect of steam on the carbonation conversion of Mn‐doped CaO was stronger than that of the original CaO. Mn in the presence of steam showed a more positive effect on CO2 capture by CaO. X‐ray photoelectron spectroscopy analysis showed that doping of Mn in CaO enhanced the transport of electrons in the carbonation of CaO, which helped to increase the carbonation rate. When steam was present in the carbonation, Mn‐doped CaO possessed a more porous structure and smaller CaO grains than the original CaO during the cycles. Simulation calculations using periodic density functional theory (DFT) showed that CO2 molecules were easier to absorb on CaO owing to the doping of Mn and the presence of steam. The synergistic enhancement effects of Mn and steam on CO2 captured the performance of CaO. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Photo-electrochemical and electrochemical water splitting are considered as effective ways to realize the efficient hydrogen evolution reaction and solve the increased energy demand. Herein, the photo-responsive MoS2 electrocatalyst modified with Co(OH)2 was synthesized on a carbon cloth (CC) by a facile approach. Benefiting from the heterogeneous interface between MoS2 and Co(OH)2, this hybrid catalyst shows superior HER activity in 1 M KOH aqueous solution with an overpotential of 117 mV at 10 mA cm−2 and a Tafel slope of 59.82 mV dec−1, which are smaller than those of MoS2/CC (an overpotential of 171 mV at 10 mA cm−2 and a Tafel slope of 90.78 mV dec−1) or Co(OH)2/CC (an overpotential of 268 mV at 10 mA cm−2 and a Tafel slope of 99.84 mV dec−1). The HER activity of Co(OH)2/MoS2/CC can be further promoted with an overpotential of 101 mV at 10 mA cm−2 due to the enhanced conductivity and exchange current density under light irradiation. Density functional theory calculations are carried out to gain a deeper insight into the effect of Co(OH)2 MoS2 interface, indicating that the introduction of Co(OH)2 can reduce the energy barrier of the initial water dissociation process and provide the hydroxyl adsorption sites, while MoS2 can promote the adsorption of hydrogen intermediates and H2 release. The synergistic effect of light irradiation and interface engineering strategy can realize efficient hydrogen evolution reaction, which can enlighten and extend to other electrocatalytic system.

A triazine-based MOFs [PCN-9(Co)] was synthesized and its photoelectrical, photophysical properties were studied. As a new photocatalyst, PCN-9(Co) displays photocatalytic hydrogen evolution from water under UV–Visible light irradiation. With the introduction of platinum complex, PCN-9-Pt was obtained and platinum complex was believed to coordinate with the N in triazine. The H2 evolution rate of PCN-9-Pt is greatly improved, about 6.8 times higher than that of PCN-9(Co). The reason is due to the fact that platinum complex plays an important role in improving the separation efficiency of photogenerated charge carriers, as verified by PL and EIS results. This result provides a new kind of idea of modifying MOFs materials with molecular complex to improve the photocatalytic activity.

Photocatalytic hydrogen evolution from water splitting driven by visible light is a promising approach to solve energy crisis and environmental problems, and noble-metal-free co-catalysts for boosting the hydrogen evolution reaction are highly desired. Herein, we explore a novel noble-metal-free Fe2P–Co2P co-catalyst for the first time to boost the photocatalytic performance of graphitic carbon nitride (g-C3N4). The resultant Fe2P–Co2P/g-C3N4 with optimum ratio exhibits a hydrogen production rate of 347 μmol h−1 g−1 in the absence of noble-metal co-catalyst, which is 87 times higher than that of pristine g-C3N4 under the same conditions. The significant enhancement in the photocatalytic performance of Fe2P–Co2P/g-C3N4 can be ascribed to the Schottky junction formed between Fe2P–Co2P and g-C3N4, which produces a strong driving force for the transfer of electrons from g-C3N4 to Fe2P–Co2P, promoting the separation and transfer of photogenerated electrons and holes. Furthermore, due to the synergistic effects between the two metal phosphides (Fe2P and Co2P), the Schottky junction in Fe2P–Co2P/g-C3N4 can produce stronger driving force than that in Fe2P/g-C3N4 and Co2P/g-C3N4, resulting in the fact that the hydrogen production rate over Fe2P–Co2P/g-C3N4 is much higher than that over Fe2P/g-C3N4 and Co2P/g-C3N4. This work may shed light on the careful design of co-catalyst by utilizing the synergistic effect of different components.

In this work, a polar molecule 4-mercaptobenzoic acid (4-MBA) is anchored on the surface of CdWO4 by forming Cd S and W S bond. Photocatalytic hydrogen evolution is significantly enhanced (about 3.41 times) after the modification. The reason is due to the modification of 4-MBA, which results in a polar surface and built-in electric field. The polar surface is confirmed by the steady state and time-resolved PL spectra, Voc and SHG results.

Effective and selective removal of Pb(II) from aqueous solution is highly desirable, but it is still a great challenge. We report here a water stable metal-organic frameworks (CAU-7-TATB), and the ligands contain N, which provides binding sites for metal ions. CAU-7-TATB exhibits fast adsorption kinetics, high adsorption capacity towards Pb(II). More importantly, CAU-7-TATB remains high prior adsorption towards Pb(II) in the presence of interfering ions like Cr(III), Co(II), Ni(II), Mn(II), Zn(II), Mg(II) and Ca(II), which is potentially applicable in removing Pb(II) from industrial water.

Ethylene (C2H4) is harmful for storage and fresh-keeping of fruits and vegetables. Photocatalytic technology is an effective and environmentally friendly approach for degrading ethylene. Herein, we first report the synthesis of a WO3 photocatalyst with high photocatalytic activity and stability using synergetic internal Fe3+ doping and superficial Pt loading for ethylene degradation under visible-light irradiation. Internal Fe3+ doping not only enhances the visible-light absorption but also improves the stability to some degree due to more positive reduction potential of Fe3+/Fe2+ than that of W6+/W5+ and separation efficiency of the photo-generated carriers. Furthermore, the loading of Pt as a co-catalyst through the photo-reduction of H2PtCl6 on the surface of Fe-doped WO3 promotes the effective transfer of photo-generated electrons and reduces the photo-corrosion of WO3. Due to the synergistic effect, extremely high degradation speed can be achieved by doping 0.25 mol% Fe and loading 0.75 wt% Pt for WO3, which exceeds that of pristine WO3 by about 3.3 times under visible-light irradiation. In addition, due to the excellent stability of Pt@Fe-doped WO3, it has good industrial application prospects in the field of photocatalysis.

In this study, we synthesized noble metal-free Co3O4 as a cocatalyst for a modified ZnO nanorod photocatalyst to achieve efficient ethylene degradation under light irradiation. The Co3O4-decorated ZnO nanorods demonstrate photocatalytic activity for ethylene oxidation that is better than that of pure ZnO and even better than that of the noble metal-based RuO2-modified ZnO. Furthermore, Co3O4-modified ZnO exhibits good stability in a six-cycle experiment. Measurement results indicate that the Co3O4 nanoparticles can effectively promote the transfer and inhibit the recombination of photogenerated electrons and holes during the photocatalytic reaction. Therefore, the Co3O4-modified ZnO nanorod photocatalyst displays excellent photocatalytic properties for ethylene degradation and can effectively realize the complete mineralization of ethylene molecules.

In this work, we developed a simple method to fabricate BiVO4 photoanode consisted of mesoporous nanoparticles (meso-BVO) by using P123 as a pore maker. Owing to the unique mesoporous nanostructure, meso-BVO exhibits higher BET surface areas, shorter hole transit distance and higher electrical conductivity than does pristine BiVO4 photoanode (BVO) consisted of solid nanoparticles. As a result, the charge separation efficiency and PEC performances of meso-BVO have been greatly improved. Meso-BVO yields a photocurrent of 2.19 mA/cm2 (1.23 V vs RHE) and IPCE of 39% (420 nm), which is 2.52 and 2 times as high as that of pristine BVO. With the assistance of Mo6+ ions doping and Co-Pi, the PEC performances could be further improved by addressing the inefficient electron transport and slow water oxidation kinetics. Co-Pi/Mo:meso-BVO yields a photocurrent of 4.57 mA/cm2 (1.23 V vs RHE) and IPCE value of 65% (420 nm). The enhanced PEC performance can be mainly ascribed to the perfect charge separation in the bulk of Co-Pi/Mo:meso-BVO photoanode. Our work provides a simple method to fabricate high efficient BiVO4 photoanodes consisted of mesoporous nanoparticles with enhanced bulk charge separation efficiencies.

Au nanoparticle (NP)- and CdS quantum dot (QD)-codecorated In2O3 nanosheets, assembled into flowerlike structure (In2O3/Au/CdS), were synthesized to facilitate photocatalytic H2 production. The optimized In2O3/Au4/CdS-12 (4 wt % Au NPs and CdS QDs were deposited for 12 cycles) displays achieved a photocatalytic hydrogen generation ability of 17.23 μmol/h (10 mg of catalyst), which is 22.97, 5.08, and 5.05 times as high as that of pristine In2O3 (0.75 μmol/h), In2O3/Au4 (3.39 μmol/h), and In2O3/CdS-12 (3.41 μmol/h), respectively. This significant improvement of H2 generation rate can be attributed to the following factors: the heterojunction at the In2O3–CdS interface and the Schottky barrier at the interface between In2O3–Au and CdS–Au improves the migration and separation of charge carriers, and the surface plasma resonance (SPR) effect of noble metal Au NPs enhances the light harvesting capacity of In2O3 and boosts the generation of hot electrons, efficiently improving the utilization rate of sunlight.

The electrocatalysts with low-cost, good stabilities, rich reserves and efficient activities are required to replace Pt-based materials for the hydrogen evolution reaction. Herein, we synthesize the low-cost MoS2/Ni3S2 heterostructure on Ni foam with efficient HER activity and good stability through optimizing the sulfur sources selection among thioacetamide (TAA), L-cysteine and thiourea. The different sulfur sources have a very important influence on the structures and morphologies of NF-MoS2/Ni3S2 composites, which may attribute to the different selective combining capacities of sulfur sources with Na2MoO4 and Ni foam. By contrast, NF-MoS2/Ni3S2-TAA shows relatively lower overpotential of 91 mV at 10 mA cm−2 and Tafel slope of 48.62 mV dec−1 than those of NF-MoS2/Ni3S2-L-cysteine (overpotential of 148 mV at 10 mA cm−2 and Tafel slope of 68.81 mV dec−1) or NF-MoS2/Ni3S2-thiourea (overpotential of 187 mV at 10 mA cm−2 and Tafel slope of 93.41 mV dec−1). The superior HER activity of NF-MoS2/Ni3S2-TAA is benefit from the higher MoS2 content and larger electrochemically active surface area. Optimizing the sulfur source selection can realize the efficient electrocatalytic hydrogen evolution of MoS2/Ni3S2 heterostructure which has an important guiding significance for the practical application in the future.

NiV-LDH as a novel electrode material has rarely been investigated in the energy storage field. Herein, novel ultrathin NiV-LDH was designed and synthesized, which displays high specific capacitance but poor stability. To further improve the stability, NiV-LDH was transformed to the sulfide named NiV-S through an ion exchange reaction (S2− replaces OH−). The obtained NiV-S maintains the ultrathin (5 nm in thickness) and porous structure, and displays higher specific capacitance (2270.4 F g−1 at 2 A g−1), compared to NiV-LDH (1502 F g−1 at 2 A g−1). What is more improtant is that the cycling stability of NiV-S is much higher than NiV-LDH, (91.9% retention after 10,000 cycles for NiV-S vs only 63% retention after 5000 cycles for NiV-LDH). The asymmetric supercapacitor assembled using ultrathin porous NiV-S as the positive electrode and activated carbon (AC) as the negative electrode was found to deliver a maximum energy density of 51 W h kg−1 at a power density of 1600 W kg−1 and 12 kW kg−1 at 23.7 W h kg−1. In addition, 98.5% of the initial capacitance retains after 10,000 continuous cycling.

Surface engineering is of importance to reduce the reaction barrier of oxygen evolution reaction (OER). Herein, the NiFe Prussian blue analogue (NiFe-PBA)-F catalyst with a multilevel structure was obtained from NiFe-PBAs via a fluorination strategy, which presents an ultralow OER overpotential of 190 mV at 10 mA cm-2 in alkaline solution, with a small Tafel slope of 57 mV dec-1 and excellent stability. Interestingly, surface fluorination engineering could achieve a controllable removal of ligands of the cyan group, contributing to keep the framework structure of NiFe-PBAs. Particularly, NiFe-PBAs-F undergoes a dramatic reconstruction with the dynamic migration of F ions, which creates more active sites of F-doped NiFeOOH and affords more favorable adsorption of oxygen intermediates. Density functional theory calculations suggest that F doping increases the state density of Ni 3d orbital around the Fermi level, thus improving the conductivity of NiFeOOH. Furthermore, based on our experimental results, the lattice oxygen oxidation mechanism for NiFe-PBAs-F was proposed. Our work not only provides a new pathway to realize the controllable pyrolysis of NiFe-PBAs but also gives more insights into the reconstruction and the mechanism for the OER process.

For Ag(I)-based photocatalysts, the photoreduction of Ag+ to metallic Ag is an unignorable issue, which is the major reason for their instability. If electrically neutral excitons rather than electrons were produced over Ag(I)-based photocatalysts, the photoreduction of Ag+ is expected to be greatly suppressed. To check this assumption, a Ag-based metal-organic framework containing pyrene, which is in favor of exciton production, is synthesized (denoted as Ag-PTS-BPY) and the structure is solved via single-crystal X-ray diffraction. Ag-PTS-BPY is applied in the photocatalytic selective oxidation of methyl phenyl sulfide, which displays high conversion and selectivity. As expected, no metallic Ag is formed after five cycles of reaction according to the results of X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy, and the high conversion is also maintained. The participation of excitons suppresses the involvement of electrons, which are believed to be the reason for the high stability of Ag-PTS-BPY.

Most Bi-based semiconductors are incapable of photocatalytic reduction reaction from a thermodynamic view, owing to relatively positive conduction band potentials (ECB ). Here, a novel Bi-based metal-organic framework (Bi-MBA, MBA=4-mercaptobenzoic acid) with excellent photocatalytic reduction activities is developed. The ECB of Bi-MBA locates at -1.38 eV, which is able to efficiently reduce O2 , CrVI and CO2 . Theoretical calculations reveal the significant contribution of organic ligand (MBA) to the conduction band. Our results provide an effective route to improve the photocatalytic reduction activities of Bi-based photocatalysts.

To produce hydrogen economically by electrolysis of water, one needs to develop a non-precious-metal catalyst that is as efficient as platinum metal. Here, we prepare such a catalyst by growing a layer of Mo2N over a layer of CeO2 deposited on nickel foam (NF) [hereafter, Mo2N /CeO2@NF] and show that the activity of this self-supported catalyst for hydrogen evolution in 1.0 M KOH is more efficient than that of the Pt/C electrode, achieving a current density of 10 mA/cm2 at a fairly low overpotential of 26 mV. Furthermore, after a long-time electrochemical stability test for 24 h at a fixed current density, the overpotential needed to attain a current density of 10 mA/cm2 is increased only by 6 mV, implying the huge potential of this method to prepare a super HER activity electrode for water splitting.

In this work, we prepared ZnGeP2 (ZGP) photocatalyst using single flat temperature zone (SFT) method in a vacuum quartz ampoule. The XRD, SEM, EDS, DRS and XPS were used to characterize the crystal structure, morphology, elemental content, optical absorption and band gap structure of ZGP. The results of photocatalytic hydrogen evolution and apparent quantum efficiency show that ZGP is a promising photocatalyst for hydrogen production both under visible and near-infrared light irradiation. In addition, it is also found that adding the common stabilizer H3PO2 and ultrasonic treatment can efficiently improve the photocatalytic activity and stability of ZGP.

Novel porous Co3O4 nanosheets (NSs) were synthesized on the flexible carbon cloth (CC) substrate by a facile hydrothermal method and applied to construct a non-enzymatic sensor for glucose detection. The sensor is based on the electro-catalytic oxidation of glucose on the surface of Co3O4 NSs. Since this particular nanostructure can provide large surface area and more active sites, the Co3O4 NSs non-enzymatic sensor exhibits excellent analytical performance, such as a high sensitivity (8506 μA mM−1 cm−2), a fast response time (less than 6 s), low detection limit of 1 μM, good selectivity, and long-term stability. The results suggest that the porous Co3O4 NSs have great potential applications in the development of sensors for enzyme-free detection of glucose.

Powder samples of mixed halide perovskite MAPbBr3–xIx (MA = methylammonium ion, CH3NH3+) were prepared by employing a facile light-assisted halide-exchange method in aqueous halide solution at room temperature. It is found that the distribution of iodide ions in the MAPbBr3–xIx particles tends to be largest on the surface and becomes lower on going into the interior so that they have a correct bandgap funnel structure that is needed for transferring photogenerated charge carriers from the interior to the surface. Consequently, the MAPbBr3–xIx/Pt powder sample (250 mg) exhibits an enhanced photocatalytic activity for a H2 evolution under visible light (100 mW cm–2, λ ≥ 420 nm) with the rate of 651.2 μmol h–1 and a solar-to-chemical conversion efficiency of 1.05%.

Graphitic carbon nitride (g-C3N4) has become an attractive photocatalyst for solar energy conversion owing to its numerous advantages. Due to insufficient solar-light absorption and fast photogenerated carriers recombination, the photocatalytic activity of traditional g-C3N4 material is unsatisfactory. In this work, P element and cyano groups ( C N) incorporated into the g-C3N4 framework is successfully fabricated by heat treatment of the mixed g-C3N4 and NaH2PO2. The cyano groups ( C N) originated from the de-protonation of C NH2 can enhance the light absorption and act as strong electron-withdrawing groups, which can promote the efficient separation of photo-generated electron-hole pairs. The P element doping can enhance the visible light absorption, shorten the band gap and suppress the recombination of photo-induced carriers. The synergistic effect of C N functional groups and P element doping results in a 6.7 times enhanced photocatalytic H2 production activity and 1.58 times enhanced photocatalytic CO2 reduction activity than that of pristine g-C3N4. Experimental analysis indicates that the enhanced photocatalytic performance is mainly attributed to the enhanced light absorption and charge separation. Our work provides a new thought to design other high performance and low-cost g-C3N4-based photocatalytic materials for solar energy conversion.

Carbon bridged graphitic carbon nitride (g-C3N4) was prepared by a facile supramolecular self-assembly method. Experimental results and theoretical calculations indicate C atoms were introduced into the g-C3N4 lattice by substituting the bridged N atoms. As a result, the delocalized big π bonds can be formed among the adjacent heptazine rings, which could both enhance the light absorption and promote the charge separation. Beneficial from the efficient charge separation and enhanced light absorption, the carbon bridged g-C3N4 exhibits high efficient photocatalytic activity, where the H2 evolution rate is about 7 times as high as that of pristine g-C3N4. This work demonstrates carbon bridged C3N4 can be fabricated by a simple supramolecular self-assembly process, which could be useful for the further development of high efficient g-C3N4 photocatalysts.

Three porous carbons were prepared by using citric acid and sucrose as carbon source, and then the AgBrO3/AgBr nanoparticles were loaded on the porous carbon by using the impregnation-precipitation method. Multi-analysis technologies were used to investigate the structures, morphologies and elements chemical states of the as-prepared samples. Rhodamine B solution was used as wastewater model to evaluate the adsorption capacity and photocatalytic activity of the hybrids. It was found that the citric acid concentration affect the number of reducing groups on porous carbon, thus affecting the structures and composition of the AgBrO3/AgBr photocatalysts. The AgBrO3/AgBr/porous carbon hybrid exhibits significant enhancements in adsorption and photocatalytic performances.