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Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds. [ABSTRACT FROM AUTHOR]

The activation capacity of molecular oxygen is an important indicator to evaluate the photocatalytic efficiency of photocatalysts. In this paper, WS2 nanosheet was deposited on hyper-crosslinked CTF-1-G (obtained by molecular expansion from covalent triazine framework CTF-1) to form a C-GW heterojunction, which promoted the photodegradation of pollutants and the activation of molecular oxygen. This novel C-GW heterojunction exhibited excellent degradation property for organic pollutants (tetracycline (TC), rhodamine B (RhB)) and activating molecular oxygen under visible light irradiation. Among them, C-GW15 could degrade 98% of 20 ppm TC in 60 min and 99% of 30 ppm RhB in 30 min, and it had the highest hydrogen generation rate and hydrogen production amount in 4 hours, which were 8.74 mmol h−1 g−1 and 34.94 mmol g−1, respectively. Meanwhile, C-GW15 had the strongest 3,3′,5,5′-tetramethylbenzidine oxidation capacity and could generate 1.83 μmol of ˙O2− in 60 min and the production of H2O2 was 20.8 μmol L−1 in 40 min. The results of this study clearly indicated that the combination of WS2 and CTF-1-G can enhance the visible light absorption capacity and photogenerated carrier separation efficiency, thus promoting the photocatalytic performance. Finally, a Z-type photocatalytic mechanism was proposed based on radical capture, molecular oxygen activation experiments and electron spin resonance analysis. These findings will extend the fundamental understanding of the Z-type photocatalytic mechanism and provide new opportunities for the rational design of CTF heterojunctions for the treatment of environmental pollution and clean energy conversion. [ABSTRACT FROM AUTHOR]

Compared with the noble metal Pt, the non-noble metal Cu as a cocatalyst exhibits a low hydrogen-evolution activity owing to its weak Cu–H bond (11 kcal mol−1), which inhibits hydrogen adsorption on Cu atoms for the hydrogen-evolution reaction of photocatalysts. Considering that the introduction of Ni with a strong Ni–H bond into Cu is beneficial for strengthening the H-adsorption ability of Cu, in this paper, the low-cost transition-metal Ni was directly introduced into Cu to form CuNi alloy nanodots as photocatalytic cocatalysts to enhance the hydrogen-evolution rate of TiO2. The CuNi alloy nanodots (2–3 nm) were photodeposited on the surface of a reduced graphene oxide (rGO)-modified TiO2 photocatalyst to generate CuNi-rGO/TiO2 by the pre-adsorption of Cu2+ and Ni2+ ions on graphene oxide (GO). Photocatalytic hydrogen-production data manifested that the CuNi-rGO/TiO2 photocatalyst achieved the highest hydrogen-production rate (10 411 μmol h−1 g−1), which was 53.7, 38.7, 1.8, and 2.2 times higher than that of pure TiO2, rGO/TiO2, Cu-rGO/TiO2, and Ni-rGO/TiO2, respectively. Density-functional-theory (DFT) calculations and mechanistic investigation showed that the introduction of Ni into Cu to form CuNi alloy nanodots improved the H-adsorption ability of Cu and optimized the H-adsorption free energy close to zero (0.046 eV) for boosting the hydrogen production rate of TiO2. This research presents a promising design of bimetallic alloy structures as H2-production cocatalysts for efficient photocatalysts. [ABSTRACT FROM AUTHOR]

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen generation in alkaline medium has become widely used in a variety of sectors. However, the possibility for additional performance improvement is hampered by slow kinetics. Because of this restriction, careful control over processes such as water dissociation, hydroxyl desorption and hydrogen recombination is required. Covalent organic frameworks (COFs) based on porphyrin and polyoxometalates (POMs) show encouraging electrocatalytic performance, offering a viable route for effective and sustainable hydrogen generation. Their specific architectures lead to increased electrocatalytic activity, which makes them excellent choices for developing water electrolysis as a clean energy conversion method in the alkaline medium. In this regard, TTris@ZnPor and Lindqvist POM were coordinated to create a new eco-friendly and highly active covalent organic framework (TP@VL-COF). In order to describe TP@VL-COF, extensive structural and morphological investigations were carried out through FTIR, 1H NMR, elemental analysis, SEM, fluorescence, UV-visible, PXRD, CV, N2-adsorption isotherm, TGA and DSC analyses. In an alkaline medium, the electrocatalytic capability of 20%C/Pt, TTris@ZnPor, Lindqvist POM and TP@VL-COF was explored and compared for the hydrogen evolution reaction (HER). The TP@VL-COF showed the best catalytic efficiency for HER in an alkaline electrolyte, requiring just a 75 mV overpotential to drive 10 mA cm−2 and outperforming 20%C/Pt, TTris@ZnPor, Lindqvist POM and other reported catalysts. The Tafel slope value also indicates faster kinetics for TP@VL-COF (114 mV dec−1) than for 20%C/Pt (182 mV dec−1) TTris@ZnPor (116 mV dec−1) and Lindqvist POM (125 mV dec−1). [ABSTRACT FROM AUTHOR]

Metal halide perovskites, such as iodine methylamine lead (MAPbI3), have received extensive attention in the field of photocatalytic decomposition of HI for hydrogen evolution, due to their excellent photoelectric properties. In this paper, a new MAPbI3-based composite, MoC/MAPbI3, was synthesized. The results show that 15 wt% MoC/MAPbI3 has the best hydrogen production performance (38.4 μmol h−1), which is approximately 24-times that of pure MAPbI3 (1.61 μmol h−1). With the extension of the catalytic time, the hydrogen production rate of MoC/MAPbI3 reached 165.3 μmol h−1 after 16 h due to the effective separation and transfer of charge carriers between MoC and MAPbI3, showing excellent hydrogen evolution rate performance under visible light. In addition, the cycling stability of MoC/MAPbI3 did not decrease in multiple 4 h cycle tests. This study used the non-precious metal promoter MoC to modify MAPbI3, and provides a new idea for the synthesis of efficient MAPbI3-based composite catalysts. [ABSTRACT FROM AUTHOR]

The designing of efficient electrocatalysts for hydrogen generation is essential for the practical application of water-splitting devices. With numerous electrochemical advantages, transition metal sulphides are regarded as the most promising candidates for catalysing the hydrogen evolution reaction (HER) in acidic media. In the present study, Ru-doped cobalt sulphide nanosheets, termed Co9S8/Ru@t (t = 24 h, 48 h, and 72 h), were obtained by varying the reaction time from 24 h to 72 h from a RuCo-PBA precursor. The role of the time period for the synthesis of Co9S8/Ru@48h is vital in increasing the number of electroactive sites and optimising the hydrogen adsorption–desorption phenomena leading to an increment in the HER activity. The electrochemical outcomes demonstrate that the optimized Co9S8/Ru@48h requires a low overpotential of just 94 mV to produce 10 mA cm−2 current density, and also exhibits a lower Tafel slope value of 84 mV dec−1 defining its faster reaction kinetics. The as-synthesized Co9S8/Ru@48h was stable for up to 20 h of constant electrolysis signifying its outstanding durability. The optimized synthetic approach and impressive electrochemical results make Co9S8/Ru@48h a suitable alternative to noble-metal-based electrocatalysts for the HER. [ABSTRACT FROM AUTHOR]

At present, the rational design and facile synthesis of highly active and low-cost photocatalysts are still facing great challenges. Herein, a series of Zn0.5Cd0.5S/NiS (x mol%) composite photocatalysts have been synthesized via a simple and mild one-pot hydrothermal method. Compared with pure Zn0.5Cd0.5S, the NiS-loaded samples exhibit enhanced photocatalytic hydrogen generation performance, in which the Zn0.5Cd0.5S/NiS-5% sample has the highest H2 production rate of 10 855 ± 461 μmol h−1 g−1 with a quantum yield of 11.82% at 365 nm, which is almost 6.3 times higher than that of pristine Zn0.5Cd0.5S. The high activity of the Zn0.5Cd0.5S/NiS nanosheets may be attributed to their distinct nanostructure, including a short transfer distance of photoinduced charge carriers, a large number of unsaturated surface atoms, and a large surface area. Moreover, the added NiS nanoparticles served as an effective cocatalyst to promote photoinduced electron transfer and enhance the surface kinetics of H2 evolution. Our work provides a simple and effective route for the preparation of sulphur-based photocatalysts, which can significantly improve the efficiency of hydrogen production from water. [ABSTRACT FROM AUTHOR]

Transition metal-based oxides have been reported as an important family of electrocatalysts for water splitting owing to their possible large-scale applications that are highly desirable for the hydrogen generation industry. Herein, we report a facile method for the preparation of phosphate-decorated NiFe oxides on nickel foam as efficient oxygen evolution reaction (OER) electrocatalysts for water oxidation. The OER electrocatalysts were developed through the pyrolysis of MIL(Fe) metal–organic frameworks (MOFs), which were modified with Ni and P species. It was found that the formation of NiO on the Fe2O3 surface (NiO@Fe2O3) can enrich electrocatalytic active sites for the OER. Meanwhile, the incorporation of P into NiO@Fe2O3 (Px-NiO@Fe2O3) creates abundant oxygen vacancies, which facilitates the surface charge transfer for OER electrocatalysis. Benefiting from the structure and composition advantages, P2.0-NiO@Fe2O3/NF exhibits the best performance for OER electrocatalysis among other prepared electrocatalysts, with an overpotential of 208 mV at the OER current density of 10 mA cm−2 and a small Tafel slope of 69.64 mV dec−1 in 1 M KOH solution. Additionally, P2.0-NiO@Fe2O3/NF shows an outstanding durability for the OER electrocatalysis, maintaining the OER current density above 20 mA cm−2 for more than 100 h. [ABSTRACT FROM AUTHOR]

As a two-dimensional (2D) nanomaterial, bulk g-C3N4 (CNB) has a low specific surface area and weak electron transport ability, which limit its application in photocatalysis. In this paper, ultrathin porous g-C3N4 nanosheets (CNS) have been synthesized by thermal oxidation etching of CNB. Compared with CNB, CNS possess a larger surface area of 234.65 m2 g−1, good dispersity in water and a high electron transfer rate. As a co-catalyst, ultra-small Pt nanoparticles (NPs) with high dispersity are successfully loaded on the surface of CNS. It is found that changing the loading method of Pt NPs in the preparation step remarkably alters the efficiency for hydrogen production. The Pt/CNS-CR photocatalyst fabricated by the chemical reduction (CR) method shows a much higher efficiency for H2 evolution from water splitting, compared to the Pt/CNS-PR photocatalyst obtained by the loading of Pt NPs by the traditional photo-reduction (PR) method. When triethanolamine (TEOA) is used as a hole sacrificial agent, the hydrogen production rate of 2.0%-Pt/CNS-CR is 7862.5 μmol g−1 h−1, which is 6.92 times higher than that of 2.0%-Pt/CNS-PR (1136.8 μmol g−1 h−1). The valence states of the Pt element in the Pt/CNS-CR and Pt/CNS-PR nanocomposites have been analyzed by X-ray photoelectron spectroscopy, respectively. At the same time, the effects of the loading amount of Pt and different sacrificial reagents on the photocatalytic H2 generation activity have also been systematically investigated. [ABSTRACT FROM AUTHOR]

The development of an efficient noble-metal-free cocatalyst is the key to photocatalytic hydrogen production technology. In this study, hierarchical Co(OH)2 nanosheet array-graphene (GR) composite cocatalysts are developed. With Eosin Y (EY) as a photosensitizer, the optimal Co(OH)2-10%GR hybrid cocatalyst presents excellent photocatalytic activity with an H2 production rate of 17 539 μmol g−1 h−1, and the apparent quantum yield for hydrogen production can reach 12.8% at 520 nm, which remarkably surpasses that of pure Co(OH)2 and most similar hybrid cocatalyst systems. Experimental investigations demonstrate that the excellent photocatalytic activity of Co(OH)2-GR arises from its unique nanosheet array architecture, which can collaboratively expose rich active sites for photocatalytic hydrogen evolution and facilitate the migration and separation of photogenerated charge carriers. It is desired that this study would supply a meaningful direction for the rational optimization of the constitute and structure of cocatalysts to achieve efficient photocatalytic hydrogen generation. [ABSTRACT FROM AUTHOR]

Piezocatalytic hydrogen evolution has emerged as a promising field for the collection and utilization of mechanical energy, as well as for generating sustainable energy throughout the day. Hexagonal CdS, an established semiconductor photocatalyst, has been widely investigated for its ability to split water into H2. However, its piezocatalytic performance has received less attention, and the relationship between its structure and piezocatalytic activity remains unclear. In this study, we prepared 3D ultrathin CdS nanoflowers with high voltage electrical response and low impedance. In pure water, without the use of any cocatalyst, CdS exhibited a piezoelectric catalytic hydrogen production rate of 1.46 mmol h−1 g−1, which was three times higher than that of CdS nanospheres (0.46 mmol h−1 g−1). Furthermore, the value-added oxidation product H2O2 was produced during the process of piezoelectric catalysis. These findings provide new insights for the design of high-efficiency piezoelectric catalytic hydrogen production. [ABSTRACT FROM AUTHOR]

The exploitation of high-performance electrocatalysts to achieve the economic electrocatalytic hydrogen evolution reaction (HER) is significant in generating H2 fuel. Enhancing the activity of the carrier catalyst by modifying trace precious metals is one of the important strategies. Herein, a hybrid material is developed by incorporating trace Ru species into a bimetallic phosphide (NiCoP) matrix on nickel foam (NF), showing a superior catalytic activity for HER. The Ru-NiCoP/NF hybrid material has plenty of heterointerfaces, improved electronic interaction, and small interfacial charge transfer resistance, improving the reaction kinetics of the HER. Remarkable, the Ru-NiCoP/NF provides a low overpotential of 96 mV at the current density of 50 mA cm−2 and high stability in 1.0 M KOH solution presenting a promising potential for hydrogen production. In addition, the Ru-NiCoP/NF sample exhibits the highest TOF value of 0.54 s−1 at an overpotential of 100 mV, which outperforms the commercial Ru/C catalyst. This study offers a promising approach for the synthesis of other precious metal supported hybrid materials. [ABSTRACT FROM AUTHOR]

Photocatalytic splitting of water for hydrogen generation is a green and renewable solution for converting solar energy to chemical energy; thus, the development of high-performance and stable photocatalytic materials has emerged as a research hotspot recently. Herein, a heterostructure composite photocatalyst of octahedral CoO uniformly modified with novel nitrogen-doped MXene quantum dots (N-MQDs) is successfully designed using a typical solvothermal approach. The optimum photocatalytic hydrogen evolution efficiency of the prepared N-MQDs@CoO heterojunction composite is 82.54 μmol g−1 h−1 with visible light, which is 16.57 times higher compared to the pure CoO. A series of photoelectrochemical tests were further performed to elucidate the photocatalytic hydrogen evolution mechanism. The remarkable improvement of activity is primarily attributed to the synergistic interaction between the closely spaced interface contacts and energy level matching among high conductivity Ti3C2 MXene quantum dots with CoO octahedra, dramatically hastening the segregation and transfer of photo-generated carriers. This study provides new ideas for the construction of MXene quantum dot-based co-photocatalysts with highly efficient photocatalytic performance and stability toward solar energy conversion applications. [ABSTRACT FROM AUTHOR]

The host–guest chemistry of O,O′-diisopropyl fluorophosphate (DFP), a phosphonofluoridate G-series chemical warfare agent simulant, was investigated in the presence of a number of octanuclear cubic coordination cage hosts. The aim was to demonstrate cage-catalysed hydrolysis of DFP at near neutral pH: however, two octanuclear coordination cages, HPEG (containing water-solubilising PEG groups) and HW (containing water-solubilising hydroxymethyl groups), were actually found to increase the lifetime of DFP in aqueous buffer solution (pH 8.7). Crystallographic analysis of DFP with a structurally related host cage revealed that DFP binds to windows in the cage surface, not in the internal cavity. The phosphorus–fluorine bond is directed into the cavity rather than towards the external environment, with the cage/DFP association protecting DFP from hydrolysis. Initial studies with the chemical warfare agent (CWA) sarin (GB) with HPEG cage in a buffered solution also showed a drastically reduced rate of hydrolysis for sarin when bound in the host cage. The ability of these cages to inhibit hydrolysis of these P–F bond containing organophosphorus guests, by encapsulation, may have applications in forensic sample preservation and analysis. [ABSTRACT FROM AUTHOR]

Co/Ni/Mo-based oxides are promising candidates for the hydrogen evolution reaction (HER). However, these electrocatalysts often exhibit unsatisfactory HER performance due to the lack of active sites. Herein, an in situ electrochemical activation strategy is proposed to modify the surface structure of a Co–Ni–Mo–O catalyst. During the HER in an alkaline electrolyte, the Co–Ni–Mo–O nanosheets display an activation period and a rough layer with low crystallinity is then formed on the surface of Co–Ni–Mo–O nanosheets with the leaching of partial Mo species. Owing to the synergistic catalysis of multiple metal components, a large electrochemically active surface area provided by the rough surface, and fully exposed active sites in the low-crystalline structure, the activated Co–Ni–Mo–O/NF shows favorable HER activity with an overpotential of only 42 mV at −10 mA cm−2. Furthermore, it remains stable at a large current density of −250 mA cm−2 for more than 400 h, outperforming almost all the oxide-based electrocatalysts. Such an electrochemical reduction activation strategy provides a feasible way for the surface modification and targeted design of advanced catalysts. [ABSTRACT FROM AUTHOR]

Among carbon allotropes, 2D graphdiyne (GDY) possesses the merits of good ductility, strong conductivity and an adjustable energy band structure. In this study, a GDY/ZnCo-ZIF S-scheme heterojunction photocatalyst has been successfully prepared by a low-temperature mixing method. Using eosin as a photosensitizer and triethanolamine as a solvent, the hydrogen production of the GDY/ZnCo-ZIF-0.9 composite reaches 171.79 μmol, which is 6.67 and 13.5 times that of the GDY and ZnCo-ZIF materials, respectively. The apparent quantum efficiency of the GDY/ZnCo-ZIF-0.9 composite at 470 nm is 2.8%. The improved photocatalytic efficiency may be attributed to the creation of an S-scheme heterojunction structure that enables efficient separation of space charges. In addition, the EY-sensitized GDY/ZnCo-ZIF catalyst endows the GDY with a special structure to provide an abundance of electrons for the ZnCo-ZIF material, thus facilitating the photocatalytic reduction reaction to produce hydrogen. A novel perspective is presented in this study regarding the construction of an S-scheme heterojunction based on graphdiyne for efficient photocatalytic hydrogen generation. [ABSTRACT FROM AUTHOR]

Reasonable design of heterojunction photocatalysts can effectively promote charge separation, thus improving their photocatalytic performance. Herein, a Bi2Fe4O9@ZnIn2S4 S-scheme laminated heterojunction photocatalyst with 2D/2D interface interaction is prepared via a hydrothermal–annealing–hydrothermal method. The photocatalytic hydrogen production rate of Bi2Fe4O9@ZnIn2S4 is up to 3964.26 μmol h−1 g−1, which is 12.1 times higher than that of pristine ZnIn2S4. In addition, its photocatalytic tetracycline degradation efficiency (99.9%) is also optimized. The enhanced photocatalytic performance can be attributed to the formation of S-scheme laminated heterojunctions that facilitate charge separation as well as strong 2D/2D laminated interface interactions favoring charge transfer. By combining in situ irradiation X-ray photoelectron spectroscopy with other characterization methods, the photoexcited charge transfer mechanism of S-scheme heterojunctions has been proved. Photoelectric chemical tests demonstrate the effectiveness of the S-scheme laminated heterojunction in improving the charge separation. This strategy provides a novel perspective for designing other high-efficient S-scheme laminated heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Hydrogen fuel plays a ubiquitous role in empowering the sustainable green energy economy. As an eco-friendly production method for hydrogen, photo-assisted water splitting is accepted to be the most reliable. However, the fabrication of stable and efficient photocatalysts is challenging. To overcome this difficulty, here we present a novel and inexpensive oxidant-promoted ultrasonic-assisted liquid phase layer exfoliation technique to fabricate a CdS/H-MoS2 nano hybrid. The newly fabricated CdS/H-MoS2 shows a hydrogen evolution rate of 162.4 mmol g−1h−1, which is 16 times higher compared to that of CdS/Pt and 67 times higher compared to that of bare CdS. Theoretical results clearly demonstrate a built-in electrostatic potential in the heterostructure junction, and that a shift in water reduction potential plays a key role in the enhancement of hydrogen production rate. We believe that the proposed experimental strategies and theoretical studies will open up a new avenue to develop new photocatalysts with high hydrogen evolution efficiency. [ABSTRACT FROM AUTHOR]

In addition to enhancing the activity of already-known photocatalysts, developing new ones is always desired in photocatalysis, giving more opportunities to approach practical applications. Most photocatalysts are composed of d0 (i.e. Sc3+, Ti4+, Zr4+) and/or d10 (i.e. Zn2+, Ga3+, In3+) metal cations, and a new target catalyst is Ba2TiGe2O8 containing both. Experimentally, it exhibits a UV-driven catalytic H2 generation rate of 0.5(1) μmol h−1 in methanol aqueous solution, which could be enhanced to 5.4(1) μmol h−1 by loading 1 wt% Pt as the cocatalyst. Most interestingly, theoretical calculations together with analyses on the covalent network could help us to decipher the photocatalytic process. The electrons in O 2p non-bonding orbitals are photo-excited to either Ti–O or Ge–O anti-bonding orbitals. The latter interconnect with each other to form an infinite two-dimensional network for electron migration to the catalyst surface, while the Ti–O anti-boding orbitals are rather localized because of the Ti4+ 3d orbitals; thus, those photo-excited electrons mostly recombine with holes. This study on Ba2TiGe2O8 containing both d0 and d10 metal cations gives an interesting comparison, suggesting that a d10 metal cation is probably more useful to construct a favorable conduction band minimum for the migration of photo-excited electrons. [ABSTRACT FROM AUTHOR]

Developing high-performance and low-cost self-supporting electrodes as pH-universal electrocatalysts for the hydrogen-evolution reaction (HER) and realizing high-quality hydrogen production at a high current density are highly desirable, but are hugely challenging. We created a self-supporting electrode with a coupled hierarchical heterostructure by simple electrodeposition followed by sulfurization. It comprised oxygen-deficient molybdenum oxide (MoO3−x) and cobalt phosphide (CoP) on nickel foam (NF), which represented a highly active pH-universal electrocatalyst for the HER at a high current density. Benefiting from a plethora of catalytic active sites, improved interfacial charge transfer, and strong electronic interaction, this type of MoO3−x@CoP/NF electrode delivered a superior catalytic performance. Overpotentials of only 100 mV, 135 mV, and 400 mV were needed to realize a high current density of 1 A cm−2 in alkaline, acid and neutral media, respectively, which were superior to those of most other well-developed materials based on non-noble metals. Our experimental work demonstrates the synergistic advantages of a MoO3−x@CoP heterostructure for improving the intrinsic catalytic performance but also paves a new path for the rational design of advanced electrodes for hydrogen generation in a wide range of pH conditions. [ABSTRACT FROM AUTHOR]

The rapid recombination of photogenerated carriers and strong photocorrosion have considerably limited the practical application of CdS in the field of photocatalysis. Loading a cocatalyst has been widely utilized to largely enhance photocatalytic activity. In the present work, a WC@C cocatalyst was prepared by a novel molten salt method and explored as an efficient noble-metal-free cocatalyst to significantly enhance the photocatalytic hydrogen evolution rate of CdS nanorods. The WC@C/CdS composite photocatalyst with a 7 wt% content of WC@C showed the highest photocatalytic hydrogen evolution rate of 8.84 mmol g−1 h−1, which was about 21 and 31 times higher than those of CdS and 7 wt% Pt/CdS under visible light irradiation. A high apparent quantum efficiency (AQY) of 55.28% could be achieved under 420 nm monochromatic light. Furthermore, the photocatalytic activity of the 7 wt% WC@C/CdS photocatalyst exhibited good stability for 12 consecutive cycles of the photocatalytic experiment with a total reaction time of 42 h. The excellent photocatalytic performance of the photocatalyst was attributed to the formation of a Schottky junction and the loading cocatalyst, which not only accelerated the separation of the photogenerated carrier but also provided a reactive site for hydrogen evolution. This work revealed that WC@C could act as an excellent cocatalyst for enhancing the photocatalytic activity of CdS nanorods. [ABSTRACT FROM AUTHOR]

Na-doped g-C3N4/NiO 2D/2D laminated p–n heterojunction nanosheets are fabricated by facile calcination and hydrothermal methods. The average thickness of g-C3N4 nanosheets is ∼1.388 nm, and the ultrathin structure allows for a high specific surface area and enough surface active sites, increasing the surface reactivity. The flower ball like structure of NiO increases the light utilization rate. Na doping accelerates charge separation and transport by increasing the electrical conductivity. The g-C3N4 and NiO nanosheets form 2D/2D laminated structures, and the spherical structure can suppress the agglomeration of 2D nanosheets, which could realize adequate interface contact and form efficient p–n heterojunctions. The p–n heterostructure builds an internal electric field to accelerate spatial charge separation. Under visible light irradiation, the photocatalytic degradation efficiency for ciprofloxacin and the hydrogen production rate of Na-doped g-C3N4/NiO are up to 99.0%, and 2299.32 μmol h−1 g−1, respectively, which are several times higher than those of the pristine one. The fabrication strategy for 2D/2D laminated heterojunctions may provide new insights for the preparation of novel laminated photocatalysts with high performance. [ABSTRACT FROM AUTHOR]

Compared with the noble metal Pt, the non-noble metal Cu as a cocatalyst exhibits a low hydrogen-evolution activity owing to its weak Cu–H bond (11 kcal mol−1), which inhibits hydrogen adsorption on Cu atoms for the hydrogen-evolution reaction of photocatalysts. Considering that the introduction of Ni with a strong Ni–H bond into Cu is beneficial for strengthening the H-adsorption ability of Cu, in this paper, the low-cost transition-metal Ni was directly introduced into Cu to form CuNi alloy nanodots as photocatalytic cocatalysts to enhance the hydrogen-evolution rate of TiO2. The CuNi alloy nanodots (2–3 nm) were photodeposited on the surface of a reduced graphene oxide (rGO)-modified TiO2 photocatalyst to generate CuNi-rGO/TiO2 by the pre-adsorption of Cu2+ and Ni2+ ions on graphene oxide (GO). Photocatalytic hydrogen-production data manifested that the CuNi-rGO/TiO2 photocatalyst achieved the highest hydrogen-production rate (10 411 μmol h−1 g−1), which was 53.7, 38.7, 1.8, and 2.2 times higher than that of pure TiO2, rGO/TiO2, Cu-rGO/TiO2, and Ni-rGO/TiO2, respectively. Density-functional-theory (DFT) calculations and mechanistic investigation showed that the introduction of Ni into Cu to form CuNi alloy nanodots improved the H-adsorption ability of Cu and optimized the H-adsorption free energy close to zero (0.046 eV) for boosting the hydrogen production rate of TiO2. This research presents a promising design of bimetallic alloy structures as H2-production cocatalysts for efficient photocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogen production is greatly limited by the low efficiency, high cost, and poor stability of electrocatalysts. Here, we report a facile one-step method to synthesize nitrogen, phosphorus co-doped carbon encapsulated FeP/CoP derived from dual metal–organic frameworks (FeP/CoP@NPC). Thanks to the synergistic effect of its unique composition and structure, the resultant FeP/CoP@NPC shows excellent catalytic HER performance with low potentials of 198, 286, and 339 mV to achieve a current density of 10 mA cm−2 in acidic, neutral, and alkaline media along with remarkable long-time durability, respectively. More importantly, this work provides an efficient strategy for fabricating high-performance and stable pH-universal catalysts toward hydrogen generation. [ABSTRACT FROM AUTHOR]

In this work, we successfully prepared composites of carbon-modified in-phase MoC–Mo2C (MoC–Mo2C@C, MMC) nanosheets with Cd0.5Zn0.5S (ZCS) nanorods. The loading of MMC nanosheets significantly improved the hydrogen production rate of ZCS nanorods. The results showed that the photocatalytic hydrogen production rate of ZCS is the highest when MMC nanosheets are 1 wt% of ZCS nanorods (1-MMC/ZCS), reaching 68.8 mmol h−1 g−1, which is 7.7 times that of pure ZCS nanorods. The 1-MMC/ZCS photocatalyst was measured with Na2S/Na2SO3 as a hole sacrifice reagent under irradiation with 420 nm monochromatic light, and the quantum efficiency of 1-MMC/ZCS was 32.9%. The carbon layer can promote the rapid transfer of photogenerated electrons, and in-phase Mo2C–MoC as the active site can synergistically improve the photocatalytic hydrogen production rate of ZCS. Most Mo2C-based materials are still used in the field of electrocatalysis. This study provides a new idea for exploring new molybdenum-based co-catalyst materials in the field of visible light catalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Green hydrogen derived from the water-electrolysis route is emerging as a game changer for achieving global carbon neutrality. Economically producing hydrogen through water electrolysis, however, requires the development of low-cost and highly efficient electrocatalysts via scalable synthetic strategies. Herein, this work reports a simple and scalable immersion synthetic strategy to deposit reduced graphene oxide (rGO) nanosheets integrated with Ni–Fe-based hydroxide nanocatalysts on nickel foam (NF) at room temperature. As a result of synergetic interactions among the hydroxides, rGO and NF, enhanced catalytic sites with improved charge transport between the electrode and electrolyte were perceived, resulting in significantly enhanced oxygen evolution reaction (OER) activity with low overpotentials of 270 and 320 mV at 100 and 500 mA cm−2, respectively, in a 1.0 M KOH aqueous electrolyte. This performance is superior to those of the hydroxide-based electrode without incorporating rGO and the IrO2-benchmark electrode. Furthermore, when the conventional OER is substituted with urea decomposition (UOR) as a proxy anodic reaction, the electrolyzer achieves 100 and 500 mA cm−2 at a lower potential by 150 and 120 mV, respectively than the OER counterpart without influencing the hydrogen evolution reaction (HER) activity at the cathode. Notably, the rGO-incorporated electrode delivers a spectacularly high UOR current density of 1600 mA cm−2 at 1.53 V vs. RHE, indicating the decomposition of urea at an outstandingly high rate. [ABSTRACT FROM AUTHOR]

A dual-phase transition metal nitride (TMN) based Co4N- WNx system has been fabricated using nitridation of CoWO4. The interface between centrosymmetric Co4N and non-centrosymmetric WNx promotes charge carrier separation. This system also shows piezoelectric behavior. The piezoelectric property has been proved using piezoelectric force microscopy (PFM) measurements. In addition, modulating the noncentrosymmetric structure of Co4N- WNx allows a hydrogen production rate of about 262.7 μmol g-1 h-1 in pure water. We also show that the piezocatalytic hydrogen evolution efficiency is satisfactory. Co4N- WNx can also help achieve simultaneous piezocatalytic hydrogen production and RhB degradation. This work provides a novel strategy for designing efficient piezocatalytic materials. [ABSTRACT FROM AUTHOR]

Developing efficient, low-cost, and environment-friendly electrocatalysts for hydrogen generation is critical for lowering energy usage in electrochemical water splitting. Moreover, for commercialization, fabricating cost-efficient, earth-abundant electrocatalysts with superior characteristics is of urgent need. Towards this endeavor, we report the synthesis of PANI--MnMoO4 nanocomposites using a hydrothermal approach and an in situ polymerization method with various concentrations of MnMoO4. The fabricated nanocomposite electrocatalyst exhibits bifunctional electrocatalytic activity towards the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) at a lower overpotential of 410 mV at 30 mA cm-2 and 155 mV at 10 mA cm-2, respectively in an alkaline electrolyte. Furthermore, while showing overall water splitting (OWS) performance, the optimized PM-10 (PANI--MnMoO4) electrode reveals the most outstanding OWS performance with a lower cell voltage of 1.65 V (vs. RHE) at a current density of 50 mA cm-2 with an excellent long-term cell resilience of 24 h. [ABSTRACT FROM AUTHOR]

In heterojunction photocatalytic materials, the size of the nanoparticles and electron--hole separation efficiency have a great influence on the photocatalytic hydrogen production activity. In this work, for the first time, a strategy of combining sulfur vacancy engineering and quantum size control for constructing CdS (MOF)/PI heterojunctions was reported. Sulfur-deficient CdS (MOF) nanoparticles with a size of 5--10 nm were derived from in situ sulfurization of Cd-MOF precursors and highly dispersed on the surface of 2D polyimide (PI). The experimental and characterization results demonstrated that CdS (MOF)/ PI heterojunctions possess broader and stronger light absorption towards the visible region than pristine PI. More importantly, a considerable amount of sulfur vacancies were introduced into CdS (MOF) nanoparticles. The presence of abundant surface and bulk sulfur vacancies created more unsaturated coordinated Cd 3c atoms, which increased the proportion of the (002) crystal planes that act as highly active crystal planes of CdS (MOF), providing more active reaction sites. The surface sulfur vacancy level located near the Fermi level serves as the photogenerated electron trap level, thereby increasing the efficiency of electron--hole separation and further prolonging the lifetime of photogenerated electrons. As a result, the 18%CdS(MOF)/PI heterojunction exhibited a higher hydrogen evolution rate of 8640 μmol g-o after 4 hours of illumination, which was 20 times higher than that of 18%CdS/PI under visible light irradiation. This work highlights the role of sulfur defects in the modification of the CdS (MOF)/PI heterojunction as a feasible strategy for improving charge separation and photocatalytic performance. [ABSTRACT FROM AUTHOR]

Engineered anion vacancy catalysts exhibit speedy activity in the field of electrocatalysis due to their tunable electronic structure and moderate free energy of adsorbed intermediates. Herein, we demonstrate a facile process of preparing multiphase phosphides with abundant phosphorus vacancies (PV) supported on nanoporous Ni(Al). X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and high-resolution transmission electron microscopy (HRTEM) reveal that the as-obtained material has ample PV induced by the AlP phase. The optimized catalyst also equips with aligned nanoflakes grown in situ on np-Ni(Al) skeletons/ligaments, thereby exposing a large specific surface area for hydrogen evolution reactions (HERs) in acidic media. Benefitting from its unique hierarchical structure and sufficient PV, the PV-np-Ni(Al)-40 electrode displays a low overpotential of 36 mV at a cathodic current density of 10 mA cm−2 and an outstanding long-term operational stability for up to 94 h with a slight decay. Density functional theory (DFT) calculations confirm that PV could induce the redistribution of electrons and significantly reduce the Gibbs free energy (ΔGH*) of 2PV-NiP2 on the P site close to PV (−0.055 eV). Moreover, the PV is beneficial for enriching the electronic states nearby the Fermi level, thereby improving the conductivity of NiP2 to achieve superior HER activity. This finding skillfully utilizes Al elements to not only create porous structures but also regulate the PV concentration, opening up an accessible route to obtain PVvia dealloying-phosphorization, and boosting the development of high-performance HER electrocatalyst. [ABSTRACT FROM AUTHOR]

Exploring efficient bifunctional electrocatalysts is of great importance for water splitting to obtain scalable and sustainable hydrogen generation. The strategy of element modification is effective for tuning the electronic structures of electrocatalysts. Herein, binder-free, phosphorus-doped NiCo2S4/CFP (Ni–Co–S–P) was synthesized under hydrothermal conditions, followed by surface phosphorization via solid reaction. The incorporation of P modulates the electronic structure of the Ni–Co–S–P catalyst, increases the electrical conductivity, and promotes the electrochemical surface area and the number of active sites, thereby improving its activity. The Ni–Co–S–P catalyst delivers a current density of 10 mA cm−2 at an overpotential of 176 mV for the hydrogen evolution reaction (HER) and an overpotential of 265 mV for the oxygen evolution reaction (OER). When assembled into an electrolyzer both as a cathode and anode, it demonstrated outstanding activity for overall water splitting to afford a potential of 1.76 V at 10 mA cm−2 with no obvious decay after 25 h. [ABSTRACT FROM AUTHOR]

Photoelectrochemical water splitting is an excellent strategy for hydrogen generation and it is pivotal to the development of photoanodes with sufficient sunlight harvesting, rapid charge separation, and enhanced electron injection efficiency. In this work, we rationally constructed a γ-graphyne/TiO2 (GY/TiO2) p–n heterojunction in which p-type γ-graphyne nanosheets were distributed in the three-dimensional space surrounding TiO2 nanotube arrays. The GY/TiO2 photoanode achieves a photocurrent density of 0.75 mA cm−2 at 1.23 V (vs. RHE), 1.7 times that of bare TiO2, and extends the electron lifetime of TiO2 from 0.51 to 1.16 ms. The improvement arises from moderate γ-graphyne modification, contributing to broadened light absorption, the suppressed recombination of electron–hole pairs, an increase in charge transfer, and a higher injection efficiency of surface electrons. This work provides a reliable approach for the utilization and conversion of sustainable solar energy. [ABSTRACT FROM AUTHOR]

Hydrogen generation during wastewater treatment has remained a long-standing challenge for the environment preservation welfare. In the present work, we have fabricated a promising bifunctional thin film-based catalyst for hydrogen generation with concurrent wastewater treatment. The prepared catalyst film is a vertically oriented thin SnS (tin monosulfide) nanosheet array on a Ni-foam (SnS/NF) obtained via a solution process, demonstrating a promising electrocatalytic activity towards the generation of green H2 fuel at the cathodic side and the decomposition of urea waste at the anodic side. Notably, while assembling two identical electrodes as cathode and anode together with a reference electrode (i.e., SnS/NF∥SnS/NF vs. RHE assembly) in 1 M KOH aqueous electrolyte containing 0.33 M urea, the electrolyzer electrolyzed urea at a lower cell potential of 1.37 and 1.43 V (vs. RHE) to deliver a current density of 10 mA cm−2 and 50 mA cm−2, respectively, for the decomposition of urea at the anodic SnS/NF electrode and green hydrogen fuel generation at the cathodic SnS/NF electrode. This activity on electrocatalytic urea decomposition lies within the best performance to those of the previously reported sulfide-based and other catalytic materials. The promising catalytic activities of the SnS catalyst film are attributed to its combined effect of self-standing nanosheet array morphology and high crystallinity, which provides abundant active sites and a facile charge transfer path between the nanosheet arrays and the electrolyte. Thus, the present work offers a green avenue to the waste-urea treatment in water and sustainable hydrogen energy production. [ABSTRACT FROM AUTHOR]

The development of durable, beneficial, and highly active non-precious metal-based electrocatalysts for hydrogen generation is a vital concern. This study proposes an effective strategy for the construction of Fe doped CoP nanosheet arrays wrapped by graphene (F0.25CP-G) on nickel foam as an efficient electrocatalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this design, the final catalyst possesses a combination of the high conductivity of graphene, great surface porosity, and the intrinsic electrocatalytic activity of the F0.25CP-G which results in high-performance electrocatalytic activity toward the HER and OER. Therefore, the as-synthesized F0.25CP-G catalyst can achieve overpotentials of 66 mV and 230 mV for the HER and OER, respectively, in KOH at 10 mA cm−2. Furthermore, a practical electrolyzer (F0.25CP-G‖‖F0.25CP-G) exhibits a current density of 10 mA cm−2 at 1.60 V along with good durability for 24 h. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) based mixed metal oxides (MMOs) are promising high temperature CO2 capture sorbents. In order to improve their CO2 capture capacity, it is crucial to bring in changes to their physicochemical properties such as morphology, particle size, surface area and activity by tuning the synthesis method. Here we report a modified amide hydrolysis method to synthesize LDHs with a mixed morphology and better CO2 capture properties. Acetate intercalated Mg–Al LDHs with two different Mg/Al ratios (3 and 4) were synthesized by employing metal hydroxides as the starting precursors and acetamide as the hydrolysing agent. The resultant LDHs crystallized in a new morphology having a combination of both fibrous and sheet like crystallites. The MMOs derived from Mg–Al-acetate LDHs retained the mixed morphology observed in the precursor LDHs. The resultant MMOs showed almost a threefold increase in the BET surface area, 316 (Mg/Al = 3) and 341 (Mg/Al = 4) m2 g−1, compared to MMOs derived from anion exchanged Mg–Al-acetate LDH (118 m2 g−1). The MMOs synthesized by acetamide hydrolysis captured 1.2 mmol g−1 and 0. 87 mmol g−1 of CO2 at 200 and 300 °C (atmospheric pressure), respectively. The CO2 capture capacity realized was increased more than twofold compared to the CO2 capture capacity of MMOs derived from anion exchanged acetate LDH (0.57 mmol g−1) tested under similar conditions. The developed MMOs showed promising CO2 capture (1.0 mmol g−1) capacity at industrially relevant CO2 concentration (14%). [ABSTRACT FROM AUTHOR]

Electron-rich, late transition metals are known to act as hydrogen-bonding (HBd) acceptors. In this regard, Pt(II) centres in square-planar environments are particularly efficient. It is however puzzling that no convincing experimental evidence is currently available for the isoelectronic neighbour Au(III) being involved in HBd interactions. We report now on the synthesis and characterisation of two series of isoleptic and isoelectronic (d8) compounds [(CF3)3Pt(L)]− and (CF3)3Au(L), where the L ligands are based on the quinoline frame and have been selected to favour HBd with the metal centre. Strong HBd interactions were actually found in the Pt(II) compounds, based on structural and spectroscopic evidence, and they were further confirmed by theoretical calculations. In contrast, no evidence was obtained in the Au(III) case. In order to find the reason underlying this general disparity, we undertook a detailed theoretical analysis of the model systems [(CF3)3Pt(py)]− and (CF3)3Au(py). This study revealed that the filled dz2 orbital is the HOMO in the case of Pt(II), but is buried in the lower energy levels in the case of Au(III). The sharply different electronic configurations involve ligand-field inversion on going from Pt to the next element Au. This is not a gradual but an abrupt change, which invalidates Au(III) as a HBd-acceptor wherever ligand-field inversion occurs. [ABSTRACT FROM AUTHOR]

To ascertain the influence of binary ligand systems [1,1-dicyanoethylene-2,2-dithiolate (i-mnt−2) and polyamine {tetraen = tris(2-aminoethyl)amine, tren = diethylene triamine and opda = o-phenylenediamine}] on the coordination modes of the Ni(II) metal center and resulting supramolecular architectures, a series of nickel(II) thiolate complexes [Ni(tetraen)(i-mnt)](DMSO) (1), [Ni2(tren)2(i-mnt)2] (2), and [Ni2(i-mnt)2(opda)2]n (3) have been synthesized in high yield in one step in water and structurally characterized by single crystal X-ray crystallography and spectroscopic techniques. X-ray diffraction studies disclose the diverse i-mnt−2 coordination to the Ni+2 center in the presence of active polyamine ligands, forming a slightly distorted octahedral geometry (NiN4S2) in 1, square planar (NiS4) and distorted octahedral geometries (NiN6) in the bimetallic co-crystallized aggregate of cationic [Ni(tren)2]+2 and anionic [Ni(i-mnt)2]−2 in 2, and a one dimensional (1D) polymeric chain along the [100] axis in 3, having consecutive square planar (NiS4) and octahedral (NiN6) coordination kernels. The N–H⋯O, N–H⋯S, N–H⋯N, N–H⋯S, N–H⋯N, and N–H⋯O type hydrogen bonds stabilize the supramolecular assemblies in 1, 2, and 3 respectively imparting interesting graph-set-motifs. The molecular Hirshfeld surface analyses (HS) and 2D fingerprint plots were utilized for decoding all types of non-covalent contacts in the crystal networks. Atomic HS analysis of the Ni+2 centers reveals significant Ni–N metal–ligand interactions compared to Ni–S interactions. We have also studied the unorthodox interactions observed in the solid state structures of 1–3 by QTAIM and NBO analyses. Moreover, all the complexes proved to be highly active water reduction co-catalysts (WRC) in a photo-catalytic hydrogen evolution process involving iridium photosensitizers, wherein 2 and 3 having a square planar arrangement around the nickel center(s) – were found to be the most active ones, achieving 1000 and 1119 turnover numbers (TON), respectively. [ABSTRACT FROM AUTHOR]

CdS/Ag2S/g-C3N4 ternary composites as photocatalysts with different amounts of Ag2S were successfully synthesized through a simple chemical deposition method. These photocatalysts were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) mapping and X-ray photoelectron spectroscopy (XPS) to obtain the information of the structure and composition. Compared with the pure samples and binary composites, CdS/Ag2S/g-C3N4 ternary composites showed enhanced hydrogen production activities, and the maximum hydrogen production rate of CdS/Ag2S(2%)/CN is about 1020.54 μmol g−1 h−1 in Na2S–Na2SO3 solution. Based on the photoluminescence and electrochemical results, the improved photocatalytic activity could be attributed not only to the synergic effect of ternary components in the composite, but also to the introduction of Ag2S that provided abundant active sites for H2 production. A possible mechanism was investigated in detail. [ABSTRACT FROM AUTHOR]

Transition metals have been considered as potential catalysts for ammonia decomposition to produce COx-free hydrogen for fuel cells. However, the facile synthesis of transition metal catalysts with small size active species, high porosity and good structural stability is still a challenge in catalytic NH3 decomposition. Herein, mesoporous Co/Al2O3 catalysts with various cobalt contents were synthesized by a facile modified sol–gel method. The catalyst 15CoAl with 15 at% cobalt content realizes the optimal catalytic NH3 decomposition performance. 92% NH3 conversion at 600 °C is achieved with a gaseous hourly space velocity (GHSV) of 24 000 cm3 gcat−1 h−1 and a hydrogen formation rate of 33.9 mmol gcat−1 min−1 at 600 °C is maintained after a 120 h long-duration stability test. Uniform small cobalt particles with high dispersion are well embedded into the skeleton of the mesoporous Al2O3 matrix. The aggregation of active cobalt species during the high temperature reaction can be effectively prevented by the mesoporous Al2O3 matrix due to the strong interaction between them, thus ensuring a good catalytic performance for ammonia decomposition. [ABSTRACT FROM AUTHOR]

A facile synthetic route, by using rhombic dodecahedral zeolitic imidazolate framework-8 (ZIF-8) as the structure template, is devoted to fabricating the ZnS/ZnIn2S4 hybrid heterojunction; the compact heterostructure was produced by combining the sulfurization of ZIF-8 and the in situ precipitation of ZnIn2S4 in one pot. The resulting ZnS nanoparticles of about 100 nm were uniformly dispersed in the folds of flower-like ZnIn2S4, whose structure is beneficial for charge transfer at the heterointerface. The additional quantities of ZIF-8 are varied to find an optimum ratio of the two components to obtain the best photocatalytic activity. In the photocatalytic hydrogen generation irradiated by simulated solar light, all the ZnS/ZnIn2S4 hybrid photocatalysts displayed improved hydrogen production rates compared to single ZnS or ZnIn2S4, and the best hydrogen production rate of 453.4 μmol h−1 g−1 is obtained by ZnS/ZIS-20, whose value is approximately 4 times higher than that of single ZnIn2S4. The electrochemical properties of the ZnS/ZnIn2S4 hybrid photocatalysts were measured to explore the charge transfer mode at the interface, and the band structure and enhanced photocatalytic hydrogen generation mechanism have been proposed. The excellent recycling properties of hydrogen production indicated the prospective applications of this kind of ZIF-derived metal sulfide in photocatalytic reactions. [ABSTRACT FROM AUTHOR]

The exploration of a highly efficient catalyst for the hydrolysis of sodium borohydride (NaBH4) is a valuable step toward a hydrogen economy. UiO-66 (Universitetet i Oslo) was synthesized via a solvothermal method using acetic acid as a modulator. The material was characterized using X-ray diffraction (XRD), nitrogen adsorption–desorption isotherms, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), temperature-programmed desorption (TPD), and transmission electron microscopy (TEM). Data analysis reveals the formation of a pure and highly crystalline phase of UiO-66 with the Brunauer–Emmett–Teller (BET) and Langmuir specific surface areas of 1125 m2 g−1, and 1250 m2 g−1, respectively. UiO-66 was analysed as a catalyst for hydrogen generation via the hydrolysis of NaBH4. The effect of the NaBH4 amount and catalyst loading was investigated. The reaction time decreased with an increase of the amount of NaBH4 or UiO-66. UiO-66 exhibited an average hydrogen generation rate of 6200 mL min−1 g−1. The high catalytic performance of UiO-66 could be due to its large surface area and acidic sites. The results suggested that UiO-66 showed high potential to catalyze the hydrogen production via the hydrolysis of hydrides. [ABSTRACT FROM AUTHOR]

Effective separation of charge carriers and substantial prolongation of charge carrier lifetime are two vital issues for a photoanode to achieve highly efficient photoelectrochemical (PEC) hydrogen generation. Herein, a Cu2O-nanoparticle-sensitized TiO2/CdS (TiO2/CdS/Cu2O) nanowire array photoanode is fabricated via subtly combining successive ionic layer adsorption and reaction with a chemical bath deposition method. Both the type-II band alignment with a stair-like structure and a p–n junction are integrated into this ternary photoanode. The fabricated photoanode shows a significant enhancement in the PEC H2 production with 4.3% efficiency. The measurements of light absorption, photoluminescence and electrochemical spectra undoubtedly demonstrate that the enhanced PEC H2 generation is ascribed to the remarkable enhancement of visible-light absorbing ability, efficient space charge separation and substantial prolongation of charge carrier lifetime, which are achieved by the synergetic effects of the type-II band alignment with a stair-like structure and the p–n junction. The enhanced PEC H2 generation demonstrates the potential of the TiO2/CdS/Cu2O nanowire arrays as a photoanode to efficiently convert solar energy into chemical fuels. [ABSTRACT FROM AUTHOR]

ε-[Al13O4(OH)24(H2O)12]7+, which shares similarity with the phosphotriesterase active site ZnII–OH–ZnII, was specially chosen to interact with the cluster α-PMo10V2O405− to form a new three-dimensional intercluster, which crystallized in the monoclinic space group P21/m with Z = 2, for the decontamination of chemical warfare agents. The experimental results showed that 50 mg of the compound decontaminated 96.4% (within 120 min) and 99.5% (within 40 min) of sulfur mustard (HD) (4 μL) and soman (GD) (4 μL), respectively, in ambient conditions. The decontamination processes followed first-order reaction kinetics with a rate constant and half-life of 0.01234 min−1 and 56.15 min for HD and 0.1198 min−1 and 5.78 min for GD, respectively. It was concluded that the α-PMo10V2O405− moiety was responsible for the catalytic oxidation of HD into non-toxic sulfoxide, while the ε-[Al13O4(OH)24(H2O)12]7+ moiety was responsible for the catalytic hydrolysis of HD and GD into nontoxic hydrolysates. Besides, the compound showed notable efficacy for the decontamination of HD on guinea pig skin and of GD on Kunming mouse skin, indicating high potential for use in human skin protection and treatment. [ABSTRACT FROM AUTHOR]

An Al13 ε-Keggin cluster, AlO4Al12(OH)24(H2O)127+, is a predominant intermediate during the hydrolysis and polymerization of aluminum as well as a highly toxic substance to plants and fishes. However, no one could clearly explain why and how a cage-like Al13 ε-Keggin cluster is formed even though it could be readily synthesized by the forced hydrolysis of Al3+. We found that the Al13 ε-Keggin cluster was spontaneously formed not in monocrystalline octosilicate but in polycrystalline magadiite by the cation-exchange reaction with unhydrolyzed Al3+. Furthermore, the Al13 ε-Keggin cluster was hardly detected in disaggregated magadiite crystals whose morphology was changed into monocrystalline crystals like octosilicate. Our findings prove that Al13 formation is necessary to relieve localized inhomogeneity and rationalize that Al13 is formed by the simultaneous co-assembly of four planar trimers and one octahedral monomer. In addition, the spontaneous formation of Al13 in heterogeneous systems could be a vital clue to its evaluation in soils and sediments. [ABSTRACT FROM AUTHOR]

In this study, Pt-substituted polyoxometalate was first modified on the surface of commercially available TiO2, forming an efficient photocatalyst with high reactivity for hydrogen evolution. During the photocatalytic process, Pt-polyoxometalates not only increase the mobility rate of electrons but also improve the separation efficiency of photoinduced electrons and holes. After photoreduction, the in situ generated Pt0 species are anchored on the surface of polyoxometalate anion, which prevents further agglomeration. Then, the in situ formed Pt0 species and polyoxometalates synergistically promote the efficiency of photoinduced electron transfer from TiO2 to the protons adsorbed on the Pt0 surface. Although the content of Pt0 in the nanocomposite is only 0.6%, the photocatalytic hydrogen production rate reaches 5.6 mmol g−1 h−1 and remains stable at 4.5 mmol g−1 h−1 after the continuous catalytic process. Due to the modification of TiO2 by Pt-substituted polyoxometalate, this nanocomposite represents a practical model that possesses highly efficient photoelectric conversion performance. The presented work not only extends the family of new TiO2-polyoxometalate-based materials but also takes a further step toward the practical application of commercial TiO2 in photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Elucidations on the structure–activity correlations of non-Pt coordination polymer (CP)-based photocatalysts are highly significant for both the enhancement in catalytic activity and large-scale industrial applications of sustainable hydrogen from water splitting. Herein, three isostructural [Cu(HL)2(R-BDC)]n (denoted as Cu-CP-R, HL = 4′-(4-hydroxyphenyl)-4,2′:6′,4′′-terpyridine, R-BDC = 2-R-1,4-benzenedicarboxylate, R = NO2, OH and Br) CPs were solvothermally synthesized by varying the substituents attached to benzenedicarboxylate, which together with two previously reported analogues (R = NH2 and H) were used as photocatalysts to systematically explore the substitution effect on the hydrogen evolution activity. These five CPs feature isomorphic layered motifs with axially elongated CuII octahedra extended alternately by ditopic HL and R-BDC2− connectors, in which R behaves structurally as a non-coordinate group. The hydrogen production rate over the Cu-CP-R photocatalysts increased from 0.21 to 2.34 mmol g−1 h−1, which followed the order of –NH2 > –NO2 > –H > –OH > –Br. Furthermore, the combined experimental and theoretical investigations reveal that the free R moiety significantly dominates the photocatalytic activity by shifting the d states of the CuII ion towards the Fermi level, controlling the potential of the conduction band and quickening the charge transfer ability. These important findings can provide informative hints for the design of high-performance, earth-abundant non-noble metal CP-based semi-conductive photocatalysts. [ABSTRACT FROM AUTHOR]

Hydrogen production with higher efficiency and lower cost is of great significance for the sustainable development of energy. Zinc cadmium sulfide (CZS) is gaining more attention owing to its excellent photocatalytic properties. However, its development is greatly limited due to photogenerated charge recombination. In this work, an innovative design with a unique 3D morphology was introduced by integrating 3DTiO2 into CZS to form a novel 3DTiO2/CZS heterojunction photocatalyst. As a result, the optimized composite achieved a very high hydrogen production rate of 75.38 mmol h−1 g−1 under visible light, which is 2.4 times higher than that of the original CZS. It can also be greatly demonstrated through photoelectrochemical tests that this unique 3D morphology contributes to the effective separation of electrons and holes, thus dramatically improving the photocatalytic activity of 3DTiO2/CZS composites. The 3DTiO2/CZS composite has a rational energy band structure, which makes it more favorable for the hydrogen precipitation reaction. It is believed that such a modification strategy based on 3DTiO2 can be applied to other similar photocatalysts as well for boosting hydrogen evolution. [ABSTRACT FROM AUTHOR]

Motivated by the recent report of a heteroleptic ruthenium bis-terpyridine complex [Ru(toltpy)(bipytpy)](PF6)2 (toltpy: 4′-(tolyl)-2,2′:6′,2′′-terpyridine; bipytpy: 4′-(4-bromophenyl)-4,4′′′:4′′,4′′′′-di-pyridinyl-2,2′:6′,2′′-terpyridine) capable of driving the photo-evolution of hydrogen with a constant rate of activity for 12 days [M. Rupp et al., Inorg. Chem., 2019, 58, 9127–9134], we investigated the impact of an internal electron donor on the photoactivity of three new ruthenium bis-terpyridine photosensitizers. We used 4′-(N,N-dimethylaminophenyl)-4,4′′-di-tert-butyl-2,2′:6′,2′′-terpyridine (Dtpy) as the donor ligand. These complexes also bear peripheral coordination sites at various positions on the terpyridine backbone, allowing for photosensitizer–catalyst interactions. Their performances in photocatalysis under blue and green light (450 and 525 nm, respectively) were measured, in the presence of triethanolamine, using a cobaloxime catalyst [Co(dmgH)2(H2O)2](BF4)2. Complexes C1[Ru(Dtpy)(pytpy)](PF6)2 (pytpy: 4′-(pyridin-4-yl)-2,2′:6′,2′′-terpyridine) and C3[Ru(Dtpy)(bipytpy)](PF6)2 appeared to have a photostability similar to that of [Ru(toltpy)(bipytpy)](PF6)2 but with lower activity rates, while C2[Ru(Dtpy)(pz2bpy)](PF6)2 (pz2bpy: 2,6-di(pyrazin-2-yl)-4,4′-bipyridine) showed a better peak activity, however, followed by a progressive decay. After 24 hours, complexes C1, C2 and C3 had reached TONs of 18, 35 and 52 under blue light and 14, 20 and 47 under green light, respectively, and were still found to be active. Their photophysical and electronic properties are discussed to rationalize the photocatalytic trends. [ABSTRACT FROM AUTHOR]

The σ-amine-borane pincer complex [Rh(PONOP)(η1-H3B·NMe3)][BArF4] [2, PONOP = κ3-NC5H3-2,6-(OPtBu2)2] is prepared by addition of H3B·NMe3 to the dihydrogen precursor [Rh(PONOP)(η2-H2)][BArF4], 1. In a similar way the related H3B·NMe2H complex [Rh(PONOP)(η1-H3B·NMe2H)][BArF4], 3, can be made in situ, but this undergoes dehydrocoupling to reform 1 and give the aminoborane dimer [H2BNMe2]2. NMR studies on this system reveal an intermediate neutral hydride forms, Rh(PONOP)H, 4, that has been prepared independently. 1 is a competent catalyst (2 mol%, ∼30 min) for the dehydrocoupling of H3B·Me2H. Kinetic, mechanistic and computational studies point to the role of NMe2H in both forming the neutral hydride, via deprotonation of a σ-amine-borane complex and formation of aminoborane, and closing the catalytic cycle by reprotonation of the hydride by the thus-formed dimethyl ammonium [NMe2H2]+. Competitive processes involving the generation of boronium [H2B(NMe2H)2]+ are also discussed, but shown to be higher in energy. Off-cycle adducts between [NMe2H2]+ or [H2B(NMe2H)2]+ and amine-boranes are also discussed that act to modify the kinetics of dehydrocoupling. [ABSTRACT FROM AUTHOR]