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[Display omitted] • Hydrothermal treatment induced biuret recrystallization to form biuret hydrate with regular morphology and large crystal size. • Biuret hydrate as precursor promoted the thermal polymerization of melem for the formation of graphitic carbon nitride (BCN-HT100) network. • The obtained BCN-HT100 possessed ultrathin nanosheet structure with high polymerization degree, large surface area and plenty of pores. • Photocatalytic overall water splitting was achieved with the AQY reaching 5.8% at 380 nm and 4.9% at 405 nm. Structure regulation (including electronic structure and morphology) for graphitic carbon nitride (g-C 3 N 4) is an effective way to promote the photocatalytic activity. Herein, an ultrathin porous g-C 3 N 4 (BCN-HT100) was synthesized by calcination of biuret hydrate. Hydrothermal treatment induced biuret recrystallization to form biuret hydrate precursor with regular morphology and large crystal size, thus promoting the polymerization of melem to form g-C 3 N 4 network. Accordingly, BCN-HT100 possessed ultrathin nanosheet structure, higher polymerization degree, larger surface area and more pores than biuret-derived g-C 3 N 4. BCN-HT100 behaved high-efficiency photocatalytic H 2 -productin activity with an apparent quantum yield (AQY) of 58.7% at 405 nm due to the enhanced utilization efficiency for photo-generated charge carriers and abundant reactive sites. Furthermore, Pt-NiCo 2 O 4 dual cocatalysts were employed on BCN-HT100 for achieving photocatalytic overall water splitting, and the AQY reached 4.9% at 405 nm. This work provides a meaningful reference to designing g-C 3 N 4 to achieve efficient solar energy conversion into hydrogen. [ABSTRACT FROM AUTHOR]

Ultrasonic field can lead to cavitation bubbles explosion, which rises a high-frequency oscillation and generates a high-frequency current in semiconductor nanoparticles in suspension. However, the effect of nanoparticle morphology on ultrasonic-triggered H 2 production is still unclear. To this end, herein, nanorods CeO 2 (nrCeO 2), CeO 2 nanocubes (ncCeO 2), and CeO 2 nanospheres (nsCeO 2) were successfully synthesized. Among them, one-dimensional nrCeO 2 had the most abundant O-vacancies. As revealed by the COMSOL simulation, nanoparticle deformation was easier in nanorods compared with nanocubes and nanospheres, resulting in more efficient charge separation and facilitating H 2 production reaction in nrCeO 2. In detail, within a 5 h' period, nrCeO 2 presented the highest H 2 production activity of 983.1 μmol g−1 h−1 with the positive charge (q+) trapping agent of CH 3 OH, and that of 278.1 μmol g−1 h−1 in pure water. This work presents a new understanding about the relationship between nanoparticle morphology and H 2 production activity, and provides a promising, efficient, and clean H 2 production approach, which can be further extended to multi-field coupling reactor. [Display omitted] • H 2 production from splitting water by CeO 2 under ultrasonic triggering was reported for the first time. • 'Power to hydrogen efficiency' of CeO 2 under ultrasonic triggering reached 7.00‰, higher than those based on photocatalysis. • H 2 production rate of nanorods CeO 2 was 1.30 and 1.54 times those of nanocubes and nanospheres CeO 2 , respectively. • Easier deformation of nanorods CeO 2 with one-dimensional characteristic resulted in more efficient charge separation. • H 2 production activity was amazing enhanced under an ultrasonic frequency of 40 kHz due to the crystal resonation of CeO 2. [ABSTRACT FROM AUTHOR]

For the dye-sensitized heterogeneous photocatalytic system, the main challenge is the design of support materials with low cost, good adsorption capacity and facilitated electron transfer ability. Herein, an amorphous/crystalline SnO 2 /BaSO 4 composite with unique leaf-like morphology composed of four protruded corners was developed by an one-pot coprecipitation method at room temperature. The low-cost crystalline BaSO 4 acted as the support material for Eosin Y (EY) sensitization and did not inhibit the light absorption of EY, and the amorphous SnO 2 uniformly coated on BaSO 4 provided good conductivity to benefit for the transport of photogenerated carriers. Therefore, under visible-light irradiation (λ ≥ 420 nm), the EY-sensitized SnO 2 /BaSO 4 showed excellent photocatalytic activity with H 2 -production rate of 263 μmol h−1, which was 7.5 times that of EY or EY-sensitized bare BaSO 4 , and the apparent quantum yield achieved to be 11.2 % at 500 nm. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of type‐II BaSnO3/g‐C3N4 heterojunction composites are prepared by anchoring BaSnO3 on g‐C3N4 via a facile solvothermal method. BaSnO3 is applied as an electron transport promoter in the field of photocatalytic H2 production under visible light for the first time. BaSnO3 shows excellent performance in collecting and transferring photogenerated electrons from g‐C3N4 to reactive sites, thus effectively inhibiting the recombination of photogenerated electron–holes. Consequently, the photocatalytic H2‐production activity of BaSnO3/g‐C3N4 composite is enhanced up to 3.2 times compared to that of pristine g‐C3N4. This work provides a meaningful reference for the application of electron transport materials in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Precursor types play crucial factors for synthesizing high-efficiency graphitic carbon nitrides (GCNs). Herein, biuret was employed as a new precursor to prepare a disordered nitrogen-defect-rich porous GCN (BCN). The crystallinity, structure and performance properties for BCN were explored by making systematic comparisons with other commonly available GCNs which were derived from conventional precursors under the identical conditions. Biuret could be the optimal choice for the preparation of high-performance GCN according to the reports so far. BCN not only possessed long-range atomic disordered structure, but also contained numerous nitrogen defects embedded into the in-planes of the disordered GCN networks, leading to extended visible-light absorption (absorption edge at 525 nm), improved separation of photoexcited charge carriers, and rich available reactive sites. The large surface area and high porosity of BCN also provided plenty of reactive sites. Consequently, ultrahigh photocatalytic H 2 production and excellent O 2 production performance were achieved for BCN, the AQY for H 2 production achieved 45.5% at 420 nm, which was one of the highest values for GCN-based photocatalysts. [Display omitted] • Graphitic carbon nitride was prepared by direct thermal polymerization of a kind of new precursor–biuret. • Biuret-derived graphitic carbon nitride (BCN) possessed disordered structure with nitrogen vacancies and cyano groups. • BCN behaved favorable visible-light absorption ability with the absorption edge at about 525 nm, the bandgap was 2.45 eV. • BCN behaved ultrahigh photocatalytic H 2 production performance, and the AQY achieved 45.5% at 420 nm. [ABSTRACT FROM AUTHOR]

A dual-precursors co-pyrolysis strategy was adopted to prepare photocatalysts of MoO 3 /g-C 3 N 4 composite from MoS 2 /melamine through a facile one-pot method. By following this strategy, MoS 2 was in-situ transformed to MoO 3 accompanying with the pyrolysis and polymerization of melamine to g-C 3 N 4 nanosheets. A set of samples about MoO 3 /g-C 3 N 4 composite containing different MoO 3 contents were prepared and the visible-light driven photocatalytic performance of samples were investigated. The photocatalytic activity was notably enhanced and the highest evolution rate for H 2 reached 13.9 times and 2.5 times that of the pristine g-C 3 N 4 and the MoO 3 /g-C 3 N 4 derived from MoO 3 /melamine, respectively. On the one hand, layered MoS 2 used as the precursor of MoO 3 contributed to the intimate contact with g-C 3 N 4 nanosheets and the high dispersity of derived MoO 3 , and on the other hand, the morphology and electronic structure of g-C 3 N 4 were actually changed by the strong interaction between the MoO 3 and g-C 3 N 4 , thus inducing an efficient Z-scheme (S-scheme) system in the composite. The above-mentioned co-operation effect in the composite resulted in the significant improvement on the activity of photocatalytic H 2 evolution. This work presented a valuable reference, by taking MoO 3 /g-C 3 N 4 as an example, for the construction of composite-photocatalyst system in visible-light-driven H 2 evolution. Image 1 • MoO 3 /g-C 3 N 4 photocatalyst was prepared by one-pot pyrolysis of MoS 2 /melamine. • H 2 -evolution rate was higher than those of g-C 3 N 4 and sample from MoO 3 /melamine. • Layered MoS 2 contributed to well dispersity and contact of derived MoO 3 on g-C 3 N 4. • Dual-precursors in-situ transformation process influenced the structure of g-C 3 N 4. • Interaction between MoO 3 and g-C 3 N 4 was enhanced to form efficient Z-scheme system. [ABSTRACT FROM AUTHOR]

Violates containing polycyclic aromatic hydrocarbons (PAHs) were precipitated in the process of fast pyrolysis and gasification of coal and organic substances. PAHs are one of bottlenecks of entire coal gasification for hydrogen production. In current work, the solubility of PAH oil droplets in supercritical water/hydrogen circumstances were investigated based on molecular dynamics simulation, which was beneficial for understanding the solubility behaviors of PAHs in supercritical water/hydrogen environment. The results showed that heavy PAHs were rather stable in the water phase. Supercritical water along with hydrogen promoted the miscibility of PAHs compared with that of pure supercritical water. Furthermore, high density and high temperature facilitated the rapid solvation of PAHs in supercritical water/hydrogen environment. This paper is expected to provide a theoretical support for the development of complete coal gasification technology for hydrogen production. Schematic illustration of an oil droplet in supercritical solvent environment. Image 1 • Solubility of PAHs in SCW/H 2 was studied by MD simulations. • Increasing temperature and density enhanced solubility behaviors. • It was observed that hydrogen penetrated water shells. • Hydrogen promoted the dispersion of PAH oil droplets. [ABSTRACT FROM AUTHOR]

Porous Cr 2 O 3 /g-C 3 N 4 composites were prepared by a facile one-pot pyrolysis method and showed enhanced visible-light-driven photocatalytic H 2 -evolution activities, with the highest rate 4.0 times of that for pure g-C 3 N 4 . During the one-pot process, accompanied by the pyrolysis of melamine to form g-C 3 N 4 , CrCl 3 ·6H 2 O acted as Cr precursor to form Cr 2 O 3 , and meanwhile functioned as pore-forming agent to increase the surface area and pore volume of g-C 3 N 4 . The cocatalytic effect of Cr 2 O 3 and the favorable textural properties of g-C 3 N 4 promoted the separation of photogenerated charge carriers, facilitated the diffusion, accumulation and adsorption of reactants, enriched the reactive sites for redox reaction, and thus resulted in the enhanced photocatalytic activities. This work presented an effective route to simultaneously optimize the compositions and micro/nano-structures of photocatalysts for H 2 evolution. [ABSTRACT FROM AUTHOR]

MoS 2 is widely applied in photocatalytic H 2 evolution to function as an efficient cocatalyst, whereas it is not yet reported that this material acted as an effective host photocatalyst in this field. Herein, MoS 2 nanosheets were prepared by a general hydrothermal process at first, and then treated with flowing NH 3 at temperatures from 400 to 900 °C to develop a series of novel MoS 2 -based photocatalysts, which showed considerable photocatalytic activities for H 2 evolution under visible-light irradiation. It was deduced from different instrumental characterizations on the physicochemical properties of photocatalysts that the enhancement of photocatalytic activity by high-temperature NH 3 treatment could be mainly attributed to the modification of surface properties (such as electric property and acid-base properties) by N, which promoted the adsorption of reactants and further accelerated photocatalytic reaction. This work presented an effective route to explore new H 2 -evolution photocatalysts by modifying the appropriate materials that were commonly employed as cocatalysts. [ABSTRACT FROM AUTHOR]

The electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS) was applied to investigate the characteristic fragmentation patterns of 1, 4-dihydropyridines using collision-induced dissociation (CID) method in positive ion mode. The intra-molecular tandem hydrogen atom migrations were observed with gas phase Na + /H + exchange by crossing five chemical bonds for 1,4-dihydropyridines. The possible rearrangement mechanisms were proposed for the first time, and the key structure of product ions were confirmed by high resolution tandem mass spectrometry and in solution hydrogen/deuterium labeling. The novel tandem hydrogen migration could be considered as a general fragmentation pattern for 1,4-dihydropyridine drugs because of their intrinsic chemical structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel series of Cr-doped HPb2Nb3O10 were synthesized. [•] Highest photocatalytic activity for H1−2x Pb2Nb3−x Cr x O10 with x =0.05. [•] The band gap energy decreased with increasing Cr doping. [•] Recombination in the bulk was restrained by doping appropriate amount of Cr3+. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment has been widely employed for material synthesis and modification. In this work, with the help of the homemade microreactor, a rapid high-temperature hydrothermal post treatment (RHTHTPT) process with fast heat transfer and short processing time was elaborately designed for graphitic carbon nitride (g-C 3 N 4). Taking advantage of high temperature and short duration time during RHTHTPT process, the RHTHTPT-derived g-C 3 N 4 reached up to a high product yield over 80%. The RHTHTPT-derived g-C 3 N 4 showed an enhanced photocatalytic H 2 -evolution activity about 5.1 times that of pristine g-C 3 N 4 under visible-light irradiation (λ > 400 nm). With systematic characterizations and the tracking of gas-liquid-solid products by RHTHTPT, it was found that the RHTHTPT could effectively enlarge the specific surface area to increase the active sites for photocatalytic H 2 -evolution reaction, abundant amino groups and the insertion of oxygen-containing functional groups in the surface of g-C 3 N 4 could realize efficient carriers separation, both of which gave rise to the improved photocatalytic H 2 -evolution performance. This work develops a promising hydrothermal strategy to regulate the in-plane structure of g-C 3 N 4 and brings a deeper understanding for the correlation between RHTHTPT-induced structure modification with photocatalytic ability, and therefore further provides some guidelines for directionally designing the special structures of g-C 3 N 4 as well as other potential materials by hydrothermal modification. [Display omitted] • A rapid high-temperature hydrothermal post treatment (RHTHTPT) was developed. • RHTHTPT-derived g-C 3 N 4 reached up to a high product yield over 80%. • RHTHTPT enlarged surface area and inserted O-containing functional group in g-C 3 N 4. • RHTHTPT-derived g-C 3 N 4 showed an enhanced photocatalytic H 2 -evolution activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Summarize the generation of various energies coupled with atmospheric water gathering. • Generalize the materials and corresponding devices developed for energy generation. • Point out directions to develop excellent energy harvesting and conversion systems. With the advantages of environmental protection, energy saving and sustainability, the technology of energy harvesting and conversion coupled with atmospheric water gathering has gradually attracted the attention of researchers under the threat of global water and energy issues. This review paper briefly described the basic working principles of energy harvesting and conversion coupled with atmospheric water gathering technology at first and then comprehensively summarized the representative materials and corresponding devices recently developed for the generation of different kinds of energies (such as electricity and chemical energy, especially hydrogen energy) by energy harvesting and conversion coupled with atmospheric water gathering technology. Electricial energy was generated based on four effects (thermoelectric, electrokinetic, triboelectric and hydrovoltaic effects) and two processes (electrochemical and photoelectric chemical processes), while hydrogen was produced based on photoelectrochemistry, photocatalysis and photovoltaic electrolysis. Based on the above analysis, it was found that the great progress, including new mechanisms and new technical paths, has been achieved on energy harvesting and conversion coupled with atmospheric water gathering technology in the last few years, but there are still many challenges to overcome and directions to explore for further development. At last, this review paper discussed some potential strategies for promoting the output efficiency and performance of energy harvesting and conversion devices. Optimizing the materials and components used in energy harvesting and conversion devices and adding energy storage modules to achieve all-weather energy supply will push this technology into a wider range of applications and better solve the global water and energy crises. [ABSTRACT FROM AUTHOR]

Eosin Y (EY)-sensitized UiO-66-NH 2 with EY chemically anchored on UiO-66-NH 2 via the bidentately bridging configuration of Zr⟵O C O→Zr was synthesized by solvothermal treatment, and presented significantly improved visible-light-driven photocatalytic H 2 -production activity (∼8 times) and stability compared with that by conventional room-temperature treatment. • A solvothermal route was developed to synthesize Eosin Y (EY)-sensitized UiO-66-NH 2. • A chemical bonding of Zr⟵O C O→Zr strengthened the linking between EY and UiO-66-NH 2. • Content of EY on UiO-66-NH 2 was increased and the transfer of charge carriers was facilitated. • H 2 evolution of EY-sensitized UiO-66-NH 2 at 120 °C was 8 times as that at room-temperature. The coupling modes of dyes with corresponding supports play key roles in the performance of dye-sensitized heterogeneous photocatalytic systems. Herein, a solvothermal method was developed to synthesize a typical kind of dye-sensitized metal-organic frameworks (MOFs), Eosin Y (EY)-sensitized UiO-66-NH 2 , in which EY was anchored on UiO-66-NH 2 via the bidentately bridging configuration of Zr⟵O C O→Zr. Such a coupling mode of chemical bonding strengthened the linking between EY and UiO-66-NH 2 , increased the content of EY on UiO-66-NH 2 , and facilitated the transfer of photogenerated electrons from EY to UiO-66-NH 2. Correspondingly, the H 2 evolution rate of EY-sensitized UiO-66-NH 2 via solvothermal treatment (2760 μmol g−1 h-1) was 8 times as that via room-temperature sensitization, with apparent quantum efficiency (AQE) ∼17.6 % at 500 nm. The as-obtained AQE and excellent stability performance exceeds most dye-sensitized photocatalytic systems for H 2 production. This work provides valuable information about developing dye-based or MOFs-based materials for efficient photocatalytic application. [ABSTRACT FROM AUTHOR]

• CoS 2 in-situ loading and S doping for g-C 3 N 4 are synchronously constructed. • Partial N atoms in g-C 3 N 4 are replaced by S atoms. • CoS 2 nanosheets as H 2 -evolution cocatalysts in-situ grow on the surface of g-C 3 N 4 nanosheets. • Co-S bonding between CoS 2 and S-doped g-C 3 N 4 enhances directed transfer of photo-generated electrons. • The noble-metal-free photocatalytic H 2 -evolution activity of g-C 3 N 4 is effectively elevated. Considering the fact of the cost control in photocatalysis, it is significant to develop the noble-metal-free photocatalysis for H 2 evolution. Herein, CoS 2 in-situ loading and S doping for g-C 3 N 4 were synchronously constructed by hydrothermal and sulfidation processes. With systematical physicochemical characterizations, it was found that partial N atoms in g-C 3 N 4 were replaced by S atoms, improving the visible-light absorption ability for more generation of photo-generated carriers. CoS 2 as an effective noble-metal-free H 2 -evolution cocatalyst induced and captured photo-generated electrons for promoting separation of photo-generated carriers synergistically with S doping. More contact between CoS 2 and g-C 3 N 4 were formed by the in-situ growth of CoS 2 nanosheets on the surface of g-C 3 N 4 nanosheets. It was important that Co-S bonding between CoS 2 and S-doped g-C 3 N 4 was built by the synchronous construction of CoS 2 in-situ loading and S doping, strengthening the directed transfer of photo-generated electrons from S-doped g-C 3 N 4 to CoS 2. Accordingly, the synergetic function of CoS 2 in-situ loading and S doping effectively elevated the noble-metal-free photocatalytic activity of g-C 3 N 4 for H 2 evolution under visible-light irradiation. [ABSTRACT FROM AUTHOR]

With increasing world energy demands, hydrogen is being widely deployed around the world as a potential alternative fuel as well as an energy carrier for future energy industry. However, due to the inherent properties of hydrogen, the safety during its production, transportation, storage and utilization is an important issue. Furthermore, the safety and reliability of hydrogen energy are necessary enabling condition for public acceptance. In this work, the concept of hydrogen energy safety and the influence factor of hydrogen safety on hydrogen economy are presented, the safety during hydrogen production, transmission and use is reviewed and several typical hydrogen accident cases are analyzed. The development of the latest technology in hydrogen energy safety is discussed, and recommendations are made to help providing a basis for future risk and reliability analysis to support safe and reliable hydrogen operation. • The hydrogen safety concept and its influence on hydrogen economy are discussed. • The hydrogen safety during its production, transmission and use are reviewed. • Typical hydrogen accidents are analyzed and lessons learned from them are discussed. • The development of the cutting-edge technologies for hydrogen safety is discussed. • The importance of reliable sensors for hydrogen leak detection is discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] Graphite carbon nitride (g-C 3 N 4) as metal-free photocatalyst has been widely studied recently in photocatalytic water reduction, which is considered as one of the promising routes to realizing the hydrogen energy-based society in the future. The generally used preparation process based on thermal polymerization of precursors easily brought the formation of aggregated nanosheets morphology, severely limiting its photocatalytic activity. Herein, the hollow tube-like morphology with porous surface was elaborately obtained by ethylene diamine tetraacetic acid (EDTA)-involved hydrothermal treatment of melamine precursor. The hollow and porous features shortened the migration distance of photo-generated carriers, trapped the incident lights, and provided more photocatalytic reactive sites, then realizing the enhanced photocatalytic H 2 -evolution activity up to 7.1 times that of pristine g-C 3 N 4. The presence of EDTA acted as the pivotal role to control the recrystallization process of melamine and its derivative, cyanuric acid, and thus to determine the framework formation of the hollow tube-like microstructure. Moreover, complete thermal decomposition of cyanuric acid during the thermal polymerization of precursors was responsible for the hollow and porous features. This work extends the morphology regulation cognition of g-C 3 N 4 based on hydrothermal treatment of precursors, and is expected to bring deep understanding and feasible strategies to design morphology-dominated highly-efficient g-C 3 N 4 photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bridging structure in g-C 3 N 4 framework was modified to promote charge transfer. • Conductive paths were created for directional transfer of photo-generated charges. • TBridging regulation made high polymerization degree and band modulation for g-C 3 N 4. • The AQY for photocatalytic H 2 evolution of modified g-C 3 N4 reached 48.7% at 425 nm. The bridging N atom in g-C 3 N 4 structure plays a decisive role in photo-generated charge transfer because it usually confines photo-generated electrons and holes in each heptazine, thus leading to severe recombination. In this work, a kind of 2-aminoterephthalic acid-derived benzene ring group with rich π-electrons was considered to integrate with bridging N to break the above-mentioned confining effect. On the basis of density-functional theory calculations and experimental analysis, this 2-aminoterephthalic acid-derived bridging structure facilitated to draw photo-generated charge out of heptazine unit, and its polarized asymmetric structure promoted the directional transfer of photo-generated charge carriers across adjacent heptazines, thus efficiently reducing the recombination. Meanwhile, the 2-aminoterephthalic acid-derived bridging structure also reinforced the connectivity of heptazine units in g-C 3 N 4 framework and led to high degree of polymerization, which thus extended the π-conjugated electronic system of g-C 3 N 4 and modulated the band structure favoring photocatalytic hydrogen production. Consequently, a high photocatalytic H 2 -production activity of 24,595 μmol h−1 g cat -1 was achieved on the bridging regulated g-C 3 N 4 under visible light, with an apparent quantum yield of 48.7% at 425 nm. [ABSTRACT FROM AUTHOR]

• Nanosized MoP was synthetized in a novel phosphorization process under an ambient-air atmosphere and assembled with g-C 3 N 4. • The incorporation of MoP into g-C 3 N 4 built a conducive highway (Mo(δ+)−N(δ−)) for electrons transfer from g-C 3 N 4 to MoP. • The optimal MoP/g-C 3 N 4 possessed H 2 -production rate of 3868 μmol h−1 g cat −1 and the corresponding AQY reached 21.6 % at 405 nm. In this work, nanosized MoP was synthetized in a novel phosphorization process at a relatively low temperature under an ambient-air atmosphere and then assembled with g-C 3 N 4 to form MoP/g-C 3 N 4 coupled photocatalyst by a mixing and heat-treating method. Significantly, the obtained noble-metal-free MoP/g-C 3 N 4 photocatalyst showed superior photocatalytic H 2 -production activity and excellent stability than most reported noble-metal-free cocatalysts modified g-C 3 N 4. The optimal MoP/g-C 3 N 4 photocatalyst possessed a H 2 -production activity of 3868 μmol h−1 g cat −1 and the corresponding AQY reached 21.6 % at 405 nm. The incorporation of nanosized MoP into g-C 3 N 4 could broaden the absorption range of visible light, built a conducive highway (Mo(δ+)−N(δ−) bond) for electrons to transfer from g-C 3 N 4 to MoP, which improved the separation and transportation efficiency of charge carriers, and reduce the energy barrier for hydrogen evolution reaction. This work provided a reliable guideline for designing novel and simple synthetic method for cocatalyst and then constructing cocatalyst/photocatalyst coupled structure. [ABSTRACT FROM AUTHOR]

A nanohybrid of CdS and HCa 2 Nb 3 O 10 with enhanced separation of charge carriers was conveniently prepared by self-assembly of negatively charged HCa 2 Nb 3 O 10 nanosheets with the existence of Cd 2+ followed by sulfuration. With CdS working as a visible light absorbent, HCa 2 Nb 3 O 10 , with a wide bandgap, showed H 2 evolution activity without cocatalysts upon visible light excitation and neutral pH (450 μmol h −1  g cat −1 ), and showed a high quantum efficiency of 7.2% at 425 nm because of enhanced charge separation. The self-assembly method rapidly realized introduction of guest materials into the interlayer space of layered perovskites from a layer-by-layer strategy, showing great potential in synthesizing novel 2D material based hybrid photocatalyst. A type II composite band structure was obtained from combination of CdS and niobates, making it possible for spontaneous charge separation. While ultra-fine nature of the guest CdS, ultra-thin nature of the host niobate nanosheets and close junction between the host and guest components facilitated charge transfer between components. Enhanced charge separation in hybrid photocatalyst is the key factor that leads to its superior photocatalytic performance in comparison with its components. This work extends photocatalytic application of wide gap niobates into visible light region. Since the unique nanostrucute and charged nature of 2D materials can be fully utilized, it is believable that more efficient photocatalytic water splitting can be realized by constructing nanosheets based hybrids in the future. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride suffers terrible recombination of photo-generated carriers and thus usually results in limited photocatalytic activity. Improving crystallinity and creating novel structure can effectively alleviate the aforementioned problem. Herein, a high-cyano groups-content and amorphous-crystalline carbon nitride isotype heterojunction (BCN-NaK) was obtain via a post treatment strategy in eutectic salt. The cyano groups acted as electron acceptors, and the intimate isotype heterojunction constructed by amorphous carbon nitride and crystalline poly-heptazine-imide built interfacial electric field. Both synergistically enabled BCN-NaK more efficient charge transfer than other amorphous and crystalline carbon nitrides. Comprehensive and systematic analysis demonstrated that the promoted charge transfer made the predominant contribution to the ultrahigh photocatalytic H 2 -production activity of BCN-NaK with an excellent apparent quantum yield of 68.9 % at 405 nm. In addition, BCN-NaK exhibited a good photocatalytic CO 2 -to-CO conversion rate of 22.8 μmol h−1 g cat −1 without adding sacrificial agent or loading metal under visible light. [Display omitted] • A high-cyano groups-content and amorphous-crystalline carbon nitride isotype heterojunction (BCN-NaK) was developed. • The cyano groups and interfacial electric field built by isotype heterojunction synergistically promoted charge transfer. • BCN-NaK showed much better photocatalytic activity than other amorphous and crystalline carbon nitrides. • BCN-NaK showed high-quantum-yield H 2 production (AQY : 68.9 % at 405 nm) and enhanced CO 2 reduction. [ABSTRACT FROM AUTHOR]

Na-doped graphitic carbon nitride was successfully developed by a one-pot preparation, that was, by simply annealing the mixture of melamine and organometallic sodium salt (ethylenediamine tetraacetic acid disodium salt). Visible-light-driven photocatalytic H 2 -evolution activity of graphitic carbon nitride was effectively enhanced by Na doping (9.2 times). It was found based on comprehensive analysis that, the absorption of visible light was improved due to the structural change of graphitic carbon nitride by Na doping, thereby promoting the generation of more photo-generated carriers. Meanwhile, the separation and transfer of photo-generated carriers were greatly enhanced by coordination of Na into big C-N rings of the triazine units. Moreover, more active sites for photocatalytic H 2 -evolution reaction were provided by the increased surface areas. [ABSTRACT FROM AUTHOR]