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Generally, photocatalytic reaction efficiency decreases quickly with increasing irradiation intensity. Thus, it is a great challenge to achieve a high reaction efficiency under strong irradiation. Volume photocatalysis (VPs) is a new strategy for improving photocatalytic reaction efficiency. Herein, hierarchically porous polymeric carbon nitride (PCN) U‐PCN‐480 as a novel volume photocatalyst is fabricated by a template‐free pyrolysis of needle‐like urea. It is found for the first time that the hierarchical pore structure endows U‐PCN‐480 with the enhanced photoabsorption ability under strong irradiation. Consequently, Pt/U‐PCN‐480 displays excellent VPs activity for hydrogen evolution in the formic acid reaction system. Notably, the activity and apparent quantum efficiency (AQE) are significantly enhanced with increasing irradiation intensity, and the AQE reaches 62.7% and 70.4% at 400 and 380 nm with the irradiation intensity of 30.5 mW cm−2, respectively, the highest values among the reported data for PCN‐based photocatalysts. This effect of enhanced activity and AQE is the result of the synergy between VPs and the enhanced photoabsorption. The findings offer an approach to resolve the difficult problem of low photocatalytic reaction efficiency under strong irradiation and open a way to develop efficient photocatalyst materials and reaction systems. [ABSTRACT FROM AUTHOR]

CdZnS and Ru doped Ru(m)/CdZnS photocatalysts were prepared by a simple hydrothermal method, and characterized by X-ray diffraction, UV-Vis absorption spectroscopy and electrochemistry techniques. Their photoactivities were evaluated by hydrogen evolution from aqueous solution containing NaS and NaSO as a hole scavenger under visible light (λ ≥ 420 nm) irradiation. Ru doping enhances the photocatalytic activity markedly. It was found that 0.10 mol% Ru doped CdZnS photocatalyst showed the highest activity. The reason for the positive effects of Ru was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Bi3+ doped Cd0.5Zn0.5S photocatalysts were prepared by a simple hydrothermal method, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), energy dispersive X-ray spectroscopy (EDX), BET and UV-Vis absorption spectroscope techniques. When Bi3+ doping content is lower, the doping ions lie at the surface lattice sites, whereas when the doping content is higher, the ions also enter the bulk lattice sites. Their photoactivities were evaluated by hydrogen evolution from aqueous solution containing Na2S and Na2SO3 as a hole scavenger under visible light (λ ≥ 420 nm) irradiation. Bi3+ doping enhances markedly photocatalytic activity. When Bi3+ doping content is 0.10 mole %, the photocatalyst exhibits the highest activity, and the average apparent quantum yield amounts to 9.71% during 30 h irradiation. The possible mechanism was discussed. [Copyright &y& Elsevier]

In this work, a noble-metal-free homogeneous system was constructed in one step with Keggin-type polyoxometalate (POM) SiW 12 O 40 4− as a catalyst, Eosin Y as a photosensitizer, and triethanolamine (TEOA) as a sacrificial electron donor for water splitting to produce hydrogen under visible-light irradiation. A two-electron reduced heteropoly blue SiW 12 O 40 6− is produced by photosensitization under visible-light irradiation. The effect of various component concentrations and POMs with different central atoms (PW 12 O 40 3− , GeW 12 O 40 4− , etc.) on hydrogen production was discussed. This simple system made of earth-abundant elements is expected to contribute toward the development of functional and efficient artificial photosynthetic system. [ABSTRACT FROM AUTHOR]

Abstract: NiS was loaded on ZnS1−x−0.5y O x (OH) y –ZnO photocatalyst by two methods (depositing NiS on the photocatalyst via impregnation with a NiS sol and via a precipitation reaction). The activity of the NiS-modified photocatalyst for hydrogen evolution from pure water and seawater was investigated using mixed electron donors (sulfide and sulfite). The activity (in pure water-electron donor solution) is dependant of the modification method and loading content of NiS. When Na2S·9H2O and Na2SO3 are added into seawater, a mixture precipitate (Mg(OH)2 and CaSO3) produces. The precipitate is detrimental to the photocatalytic hydrogen evolution over the unmodified ZnS1−x−0.5y O x (OH) y –ZnO. However, for the NiS-modified photocatalyst, the detrimental effect decreases notably. Interestingly, the activity of the modified photocatalyst in seawater-electron donor solution (with the precipitate) is higher than that in the pure water-electron-donor solution (without the precipitate). The possible mechanism was discussed. [Copyright &y& Elsevier]

[Display omitted] • Ni 12 P 5 was in situ anchored on ZnIn 2 S 4 via a solvothermal route. • The intimate interface between Ni 12 P 5 and ZnIn 2 S 4 can promote the charge transfer from ZnIn 2 S 4 to Ni 12 P 5. • ZnIn 2 S 4 loaded with 6 wt% Ni 12 P 5 exhibits the best hydrogen production activity and excellent stability. • The possible photocatalytic mechanism was discussed. It is a great challenge to develop efficient, stable and inexpensive hydrogen evolution reaction (HER) catalysts for photocatalytic water-splitting. In this paper, Ni 12 P 5 (NP) was in situ anchored on the surface of ZnIn 2 S 4 (ZIS) via a solvothermal route with nickel chloride and red phosphorus as ingredients. Using triethanolamine as sacrificial agent, the photocatalytic hydrogen evolution activity of NP/ZIS was studied under visible light irradiation. At the same time, the composition, structure, morphology and photoelectrochemical properties of the as-obtained samples were analyzed through a sequence of characterization techniques. ZIS loaded with 6 wt% NP (6NP/ZIS) exhibits the best hydrogen evolution activity and excellent stability. The H 2 evolution rate of 6NP/ZIS is 5.4 times higher than that of pristine ZIS and well beyond that of the physical mixture (6NP + ZIS) or even that of the optimal Pt/ZIS under the same conditions. The maximal apparent quantum yield (AQY) of 22.7 % at 400 nm is achieved, superior to the most reported performance of ZnIn 2 S 4 -based photocatalysts for HER. The anchor of NP can not only enhance the visible light absorption intensity, but also reduce the HER overpotential. More importantly, the intimate interface between ZIS and NP can promote the separation and migration of photo-excited carriers, thereby enhancing the activity of photocatalytic hydrogen evolution. The possible photocatalytic reaction mechanism was discussed. [ABSTRACT FROM AUTHOR]

Abstract: It is important to construct a stable and efficient dye sensitization system for visible-light photocatalytic hydrogen evolution. Eosin Y (EY)-sensitized α-[AlSiW11(H2O)O39]5− (AlSiW11) (an Al3+ substituted Keggin polyoxometalate (POM)) for the hydrogen evolution under visible light irradiation (λ > 420 nm) has been carried out in the presence of triethanolamine as electron donor and Pt as co-catalyst. EY can coordinate with AlSiW11. The coordination association between AlSiW11 and EY is beneficial to the charge transfer from EY to AlSiW11 and to stability of EY. The system displays efficient and stable photocatalytic hydrogen evolution. The average apparent quantum efficiency and turnover number of EY during 20 h irradiation (λ > 420 nm) are 10.3% and 473, respectively. The highest quantum efficiency amounts to 28.0% under 520 nm monochromatic light irradiation. The present study highlights linking between dye and POM molecule as a way to develop new visible-light stable photocatalyst or system. [Copyright &y& Elsevier]

Abstract: Effects of α-d- and β-d-glucose as electron donors on photocatalytic hydrogen generation over Pt/TiO2 have been investigated. α-d-Glucose exhibits better photocatalytic activity for hydrogen evolution than β-d-glucose. The effects of initial pH of the anomer solutions on photocatalytic hydrogen generation have also been studied. Weak basic condition is favorable for the photocatalytic hydrogen generation. There is a large activity difference between α-d- and β-d-glucose under neutral condition, while the difference is very small under basic and acidic conditions. The possible mechanism was discussed. [Copyright &y& Elsevier]

Abstract: Photocatalytic hydrogen production was investigated over ZnS1−x−0.5y O x (OH) y –ZnO using sulfide ion (Na2S–Na2SO3) as an electron donor from NaCl saltwater. NaCl can affect markedly the activity for photocatalytic hydrogen production, depending on NaCl concentration. When NaCl concentration is lower, the activity is lower than that in pure water, whereas when NaCl concentration is higher, the activity is higher than that in pure water. NaCl decreases not only the surface charge of ZnS1−x−0.5y O x (OH) y –ZnO but also the surface hydration. When ZnS1−x−0.5y O x (OH) y –ZnO was impregnated with the electron donor (Na2S–Na2SO3), ZnO was transformed partly into ZnS. The impregnated ZnS1−x−0.5y O x (OH) y –ZnO exhibits higher activity than the non-impregnated one. The possible mechanisms were discussed. [Copyright &y& Elsevier]

Abstract: ZnS coated ZnIn2S4 (ZnS–ZnIn2S4) photocatalysts were prepared in methanol by a facile solvothermal process. The photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), UV–Vis diffusive reflectance spectroscopy (DRS), BET, and electrochemistry measurements. ZnS–ZnIn2S4 photocatalysts have hexagonal crystal phase and complex morphology such as micro-spheres, micro-tubes and micro-ribbons. Using glucose as an electron donor, photocatalytic hydrogen generation over Pt/ZnS–ZnIn2S4 was investigated. The results show that photoactivity of hydrogen generation over Pt/ZnS–ZnIn2S4 was improved notably with simultaneous degradation of glucose. The factors which affect photocatalytic hydrogen generation, such as composition of ZnS-ZnIn2S4, initial concentration of glucose and concentration of NaOH, were investigated. The prepared ZnS–ZnIn2S4 photocatalysts exhibit better activity for hydrogen generation than pure ZnIn2S4, which may be attributed to enhancement of the adsorption of glucose by ZnS on the ZnIn2S4 surface. The effect of glucose concentration on the hydrogen generation rate is consistent with a Langmuir model. The basic condition is favorable for the photocatalytic hydrogen generation. A large number of ·OH radicals generated in ZnS–ZnIn2S4 system, have been tested by a TA-FL (terephthalic acid-fluorescence) method. A possible mechanism was discussed. [Copyright &y& Elsevier]

Abstract: An efficient visible-light active photocatalyst of multilayer-Eosin Y-sensitized TiO2 is prepared through linkage of Fe3+ between not only TiO2 and Eosin Y but also different Eosin Y molecules to form three-dimensional polymeric dye structure. The multilayer-dye-sensitized photocatalyst is found to have high light harvesting efficiency and photocatalytic activity for hydrogen evolution under visible light irradiation (λ >420nm). On the optimum conditions (1:1 initial molar ratio of Eosin Y to Fe(NO3)3, initial 10×10−3 M Eosin Y, and 1.0 wt% Pt deposited by in situ photoreduction), its maximal apparent quantum yield for hydrogen evolution is 19.1% from aqueous triethanolamine solution (TEOA aq). The present study highlights linking between dye molecules via metal ions as a general way to develop efficient visible-light photocatalyst. [Copyright &y& Elsevier]

Abstract: A composite visible light photocatalyst was prepared through co-precipitation of Zn(NO3)2 in the mixed solution of aqueous Na2S and NaOH, and calcination in N2 atmosphere. The photocatalyst was characterized by thermogravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), UV–vis diffusive reflectance spectroscopy (DRS), BET and electrochemistry measurements. Its activity was evaluated by hydrogen production from an aqueous solution containing Na2S and Na2SO3 as hole scavengers under visible light (λ ≥420nm) irradiation. The photocatalyst is a mixture of basic zincoxysulfide (ZnS1−x−0.5y O x (OH) y ) solid solution and ZnO or only the solid solution. ZnS1−x−0.5y O x (OH) y , which was visible light active, was a solid solution of ZnS with dissolved oxygen and hydroxide groups. Hydroxide groups are very important in the formation and stabilization of the solid solution. The precipitation and calcination temperatures as well as the precursor composition of ZnS1−x−0.5y O x (OH) y have great influence on the photocatalytic activity. With 1:1 calculated molar ratio of ZnS to ZnO (or Zn(OH)2), ZnS1−x−0.5y O x (OH) y photocatalyst prepared via co-precipitation at 373K and calcination at 673K under N2 atmosphere exhibits the highest activity. Its apparent quantum yield without noble metal cocatalyst is ca. 3.0% under visible light irradiation. [Copyright &y& Elsevier]

It is highly desirable to develop efficient and cost-effective composite catalysts to replace noble metal Pt for hydrogen evolution reaction (HER). For an excellent HER catalyst, both the adsorption and desorption of intermediate H atoms on it should be easy. However, except metal platinum, most individual species cannot satisfy this requirement. Fe-B is an active HER catalyst with strong ability to adsorb H atoms. In our previous work, we found that when Fe-B alloy was decorated with metal Fe particles (Fe-B@Fe), the resultant composite displayed a significant synergic effect for HER compared to single Fe-B and Fe. The role of the decorated Fe on Fe-B is to improve H 2 desorption. Because the desorption of H 2 molecule from Ni is easier than from Fe, we expect Fe-B@Ni to be a more efficient HER catalyst than Fe-B@Fe. Herein, we transform Fe-B@Fe into Fe-B@Ni by a facile displacement reaction. As a proof of concept, the as-prepared Fe-B@Ni catalyst exhibits much higher electrocatalytic and photocatalytic activity for hydrogen production than the pristine Fe-B@Fe. At the current density of −100 mA cm−2, the overpotential of Fe-B@Ni in 1.0 mol L−1 KOH is close to that of 20 wt% Pt/C. The highest apparent quantum yield (AQY) for dye-sensitized photocatalytic hydrogen evolution reaches 51% at 420 nm. The possible mechanisms have been proposed. These findings provide new insights for designing and fabricating new HER composite catalysts for electrocatalytic and photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

The construction of a composite photocatalyst with two suitable semiconductors is an effective strategy to improve the transport and separation of the photoexcited carrier pairs. Herein, it is the first time to report the new concept of anisotropic heterojunctions (H and J type) in layered ZnIn 2 S 4 nanosheets as an example. Due to the anisotropic conductivity, the resistance of the electron transfer along ZnIn 2 S 4 layers to a second semiconductor (J type heterojunction), is much less than that across the layers (H type heterojunction). As a result, the J type heterojunction can achieve higher photocatalytic activity than H type one. Furthermore, ZnIn 2 S 4 /In(OH) 3 heterojunction with the J type structure was successfully fabricated by a simple approach, namely, In(OH) 3 was selectively assembled at the rims of ZnIn 2 S 4 nanosheets via hydrothermal transformation of the precursor precipitate with its mother solution obtained by adding Na 2 S into the solution of stoichiometric In 3+ and excessive Zn 2+ . The intimate-contact J type heterojunction with in-situ photodeposited Pt shows efficient photocatalytic H 2 evolution under visible irradiation, leading to a high apparent quantum yield of 38.3% at 420 nm with a low optimal Pt loading of 0.25 wt%. This work provides a new insight for the development of efficient heterojunction photocatalysts with layered semiconductors. [ABSTRACT FROM AUTHOR]

A new concept of volume photocatalysis of of solid catalysts is created, and an efficient reaction system constructed using low polymeric carbon nitride as a photocatalyst and biomass-derived formic acid as a reactant. The apparent quantum yield for photocatalytic hydrogen evolution reaches 51.9% at 400 nm in formic acid reaction system. • It is the first time to propose the concept of volume photocatalysis of solid catalysts. • Low polymeric carbon nitride (PCN) can act as a volume photocatalyst. • An efficient PCN photocatalytic H 2 evolution is achieved in formic acid reaction system. • Apparent quantum yield for photocatalytic H 2 generation at 400 nm reaches 51.9%. • This work provides a new strategy to enhance photocatalytic reaction efficiency. Conversion of solar energy into H 2 via photocatalytic reforming of biomass or its derivatives is an attractive technology. However, the photocatalytic reaction efficiency is usually low due to the high recombination of photogenerated electrons and holes. Herein, we demonstrate a new concept and strategy of volume photocatalysis of solid catalysts and construct an efficient reaction system using low polymeric carbon nitride (PCN) as a volume photocatalyst and biomass-derived formic acid as a reactant. In this system, PCN allows the reactant to enter its bulk and in-situ scavenge photogenerated holes, which greatly inhibits the recombination of the electrons and holes. As a result, the left electrons can effectively migrate from the bulk to the surface of PCN to reduce protons/water molecules into hydrogen. The apparent quantum yield (AQY) for photocatalytic hydrogen evolution reaches 51.9% at 400 nm in formic acid reaction system. These findings provide new insights for understanding heterogeneous photocatalysis. [ABSTRACT FROM AUTHOR]