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Photosystem II (PSII) uses light energy to oxidize water and to reduce plastoquinone in the photosynthetic electron transport chain. O2 is produced as a byproduct. While most members of the PSII research community agree that O2 originates from water molecules, alternative hypotheses involving bicarbonate persist in the literature. In this perspective, we provide an overview of the important roles of bicarbonate in regulating PSII activity and assembly. Further, we emphasize that biochemistry, spectroscopy, and structural biology experiments have all failed to detect bicarbonate near the active site of O2 evolution. While thermodynamic arguments for oxygen-centered bicarbonate oxidation are valid, the claim that bicarbonate is a substrate for photosynthetic O2 evolution is challenged. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have been regarded as promising photocatalytic materials. However, the sluggish diffusion of photoinduced charges in a single‐component COF remains the obstacles that have to be overcome. Here, we demonstrate a synthesis of a COF bearing dual cocatalysts Co3O4 and Re complex as photocatalyst for water oxidation. The dual cocatalysts are coordinated on the COF, and enable the spatial separation of photoinduced charges. The generated electrons were attracted to Re moiety, while the holes were localized on Co3O4 cocatalyst for water oxidation to produce O2 product. The synergy of dual cocatalysts of COF promote the charge separation and redox reaction. Moreover, hydroxyl radicals generated from the hydration of COF contribute to O−O bond formation, which is the key step of O2 formation. Accordingly, an excellent O2 production rate of 400 μmol g−1 h−1 under visible light irradiation was obtained. This work may pave the way to the development of highly efficient COF photocatalysts for solar energy conversion. [ABSTRACT FROM AUTHOR]

Synthesis of N-doped MgTiO3 with an ilmenite structure was examined as a new ilmenite-type oxynitride material. N-doped MgTiO3 with Scsubstitution was successfully obtained by flux-assisted nitridation using a LiCl-KCl eutectic under pure NH3 or 5% NH3. The oxynitrides gave visible light absorption which MgTiO3 did not show, and were active for sacrificial O2 evolution using AgNO3 under visible light irradiation. [ABSTRACT FROM AUTHOR]

In this research, a new nanocomposite was synthesized via the sol-gel method by covalent immobilizing of di -substituted Keggin-type heteropolyanion containing cobalt (PW 10 Co 2) on the surface of manganese oxide (MnO 2) ceramic. The desired nanocomposite (PW 10 Co 2 @MnO 2) was used as an effective heterogeneous catalyst in the water oxidation reaction for oxygen evolution. The PW 10 Co 2 @MnO 2 nanocatalyst was identified through Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) methods in detail. After confirming the preparation of the PW 10 Co 2 @MnO 2 , its catalytic activity in the water splitting reaction was assessed in the presence of cerium (Ⅳ) ammonium nitrate (CAN) as an efficient oxidant at different pH (pH = 7 and 9). The PW 10 Co 2 @MnO 2 nanocatalyst demonstrated turnover number (TON), turnover frequency (TOF), and O 2 evolution of 520.12 m m o l O 2 m o l C o. s , 178 m m o l O 2 m o l C o , and 0.003 m g O 2 L. S , respectively, which are the highest values at pH = 9 in the water oxidation process. Moreover, the effect of CAN concentration, pH, and the amount of KOH was assessed on the catalytic activity, and a plausible reaction mechanism was proposed. In the present study, the PW 10 Co 2 @MnO 2 nanocatalyst provides valuable insights into the design of other catalysts for the water oxidation reaction and beyond. • The PW 10 Co 2 @MnO 2 nanocatalyst was synthesized via sol-gel method. • The catalytic activity of nanocomposite was tested on the water oxidation. • The water splitting was assessed in the presence of CAN as an oxidant at different pH. • The nanocatalyst was found to be efficient for water oxidation process. [ABSTRACT FROM AUTHOR]

The development of bifunctional catalysts for solar-driven hydrogen and oxygen evolution has been regarded as a challenging but interesting research topic. As promising multi-electron-transfer catalysts, reported polyoxometalate (POM)-based catalysts often contain only a single type of transition metal substitution for driving either hydrogen production or oxygen evolution. Herein, a viable two-step parental substitution approach has been developed to synthesize two structurally-new mixed-transition-metal-substituted polyoxometalates (mixed TMSPs), K6Na4[Mn2Ni2(H2O)2(PW9O34)2]·21H2O ({Mn2Ni2}) and K10[Mn2Co2-(H2O)2(PW9O34)2]·35H2O ({Mn2Co2}), using Na12[Mn2Na2(PW9O34)2]·36H2O ({Mn2Na2}) as the precursor. Characterization results confirmed the nearly quantitative substitution of Na+ with Ni2+ and Co2+ ions. X-ray absorption fine structure (XAFS) spectroscopy revealed that the Mn atoms are preferentially located in the internal positions of the central belt while Ni and Co atoms preferentially reside in the external, solvent-accessible positions. Benefiting from the second substitution of catalytically active transition metals, the resulting {Mn2Ni2} and {Mn2Co2} can be utilized as Janus catalysts towards H2 evolution and O2 evolution under visible light irradiation with greatly-enhanced activity compared to that of parental {Mn2Na2}. The introduction of mixed transition metals into POM structures not only enriches the POMs family, but also provides an effective strategy to control electronic structures and catalytic properties of POM-based catalysts at the atomic level. [ABSTRACT FROM AUTHOR]

Ta3N5 is regarded as a promising photocatalyst for solar water splitting because of its excellent visible light absorption characteristics and simple composition. Conventional Ta3N5 photocatalysts prepared from oxide precursors typically comprise aggregated polycrystalline particles with defects and grain boundaries that reduce the water oxidation activity of the material. In the present work, well-dispersed Ta3N5 nanoparticulate single crystals were synthesized via a mild nitridation process using pure Ta metal nanopowder or Ta nanopowder mixed with NaCl. The resulting high-quality Ta3N5 nanoparticles, after loading with an oxygen evolution cocatalyst, exhibited impressively high photocatalytic performance during O2 evolution from a sacrificial AgNO3 solution, with an apparent quantum yield of 9.4% at 420 nm. Our findings suggest a new approach to the facile fabrication of nanostructured single-crystal photocatalysts for efficient solar water splitting, based on the use of metal nanopowders. [ABSTRACT FROM AUTHOR]

In spite of the numerous advances in the development of H2 and O2 evolutions upon water splitting, the separation of H2 from O2 still remains a severe challenge. Herein, the novel dual‐functional nanocatalysts Pd/carbon nanosphere (CNS), obtained via immobilization of ultrafine Pd nanoparticles onto CNS, are developed and employed for both selective H2 generation from HCOOH dehydrogenation and O2 evolution from H2O2 decomposition. In these reactions, the highest activities for Pd/CNS‐800 (i.e., calcinated at 800°C) are 2478 h−1 and 993 min−1 for H2 and O2 evolution, respectively. The highly efficient and selective "on–off" switch for selective H2 generation from HCOOH is successfully realized by pH adjustment. This novel and highly efficient nanocatalyst Pd/CNS‐800 not only provides new approaches for the promising application of HCOOH and H2O2 as economic and safe H2 and O2 carriers, respectively, for fuel cells, but also promotes the development of "on‐off" switch for on‐demand H2 evolution. [ABSTRACT FROM AUTHOR]

The successful separation of photoexcited charge carriers and their effective utilization are crucial for overcoming the slow kinetics of the four-electron process for photocatalytic oxygen evolution. Herein, a novel strategy utilizing urea as a source of N-doping on Ca _2 Nb _3 O _10 nanosheets is adopted, followed by the successful deposition of Co single atoms (Co-SAs) to achieve a synergistic effect. The presence of N-dopants and Co-SAs is validated via various experimental techniques. It is also observed that the presence of N-doping contributed towards the deposition of higher content of Co-SAs (0.21 wt%) in Ca _2 Nb _3 O _10− _x N _x -Co _SA nanosheets compared to 0.15 wt% for non-doped Ca _2 Nb _3 O _10 -Co _SA . The optimized Ca _2 Nb _3 O _10− _x N _x -Co _SA nanosheets exhibited an impressive photocatalytic O _2 evolution of ∼727.22 µ mol g ^−1 h ^−1 via the synergy of N-dopants and Co-SAs. As a result, the O _2 evolution response of Ca _2 Nb _3 O _10− _x N _x -Co _SA is 3.6 times higher than that of pristine Ca _2 Nb _3 O _10 nanosheets (201.26 µ mol g ^−1 h ^−1 ), 2.24 times better than Ca _2 Nb _3 O _10− _x N _x nanosheets (323.42 µ mol g ^−1 h ^−1 ), and 1.77 times higher compared to Ca _2 Nb _3 O _10 -Co _SA , (409.33 µ mol g ^−1 h ^−1 ), which clearly demonstrated the synergistic effect of N-dopants and Co-SAs in Ca _2 Nb _3 O _10− _x N _x -Co _SA nanosheets. Based on the findings of various characterization techniques, the co-presence of N-dopants and Co-SAs is observed to contribute towards better charge carrier separation, and utilization to achieve superior photocatalytic response. Thus, this study presents a novel approach for incorporating N-dopants and Co-SAs on Ca _2 Nb _3 O _10 nanosheets, which can be extended to a wide range of nanosheets produced by the soft chemical exfoliation method.

Abstract In spite of the numerous advances in the development of H2 and O2 evolutions upon water splitting, the separation of H2 from O2 still remains a severe challenge. Herein, the novel dual‐functional nanocatalysts Pd/carbon nanosphere (CNS), obtained via immobilization of ultrafine Pd nanoparticles onto CNS, are developed and employed for both selective H2 generation from HCOOH dehydrogenation and O2 evolution from H2O2 decomposition. In these reactions, the highest activities for Pd/CNS‐800 (i.e., calcinated at 800°C) are 2478 h−1 and 993 min−1 for H2 and O2 evolution, respectively. The highly efficient and selective “on–off” switch for selective H2 generation from HCOOH is successfully realized by pH adjustment. This novel and highly efficient nanocatalyst Pd/CNS‐800 not only provides new approaches for the promising application of HCOOH and H2O2 as economic and safe H2 and O2 carriers, respectively, for fuel cells, but also promotes the development of “on‐off” switch for on‐demand H2 evolution.

Electrochemical water splitting is one of the most important method for energy conversion and storage. For this, the design and development of a low-cost robust electrocatalyst are highly desirable. In this study, Cobalt-based electrocatalyst for Oxygen Evolution Reaction was synthesized by thermal treatment of Cobalt-dehydroacetic acid (Co-DHA). The as-synthesized Co nanostructures and Co-DHA crystals were characterized with powder X-ray diffraction, X-ray photoelectron spectroscopy thermo-gravimetric analysis, and field emission scanning electron microscopy. The electrochemical O2 evolution study shows the overpotential (at 10 mV/cm−2) correspond to 294 mV vs reference hydrogen electrode (RHE) for K-300 (Co3O4@300), whereas K-500 (Co3O4@500) shows 170 mV vs RHE values in 1 M KOH solution, respectively. Similar trends have been observed for electrochemical O2 evolution studies in 0.5 M H2SO4, where K-300 and K-500 shows the overpotential (at 10mV/cm−2) of 234 mV vs RHE, and 199 mV vs RHE, respectively. The outcomes show better catalytic efficiency of K-500 as compared to K-300.

Living systems that can spontaneously exhibit directional motion belong to diverse classes such as bacteria, sperm and plankton. They have fascinated scientists in recent years to design completely artificial or biohybrid mobile objects. Natural ingredients, like parts of plants, have been used to elaborate miniaturized dynamic objects, which can move when they are combined with other, non‐natural, building blocks. Herein, we report that the precise structural tailoring of natural plant leaves allows generating a spatially predefined and confined release of oxygen gas, due to the conversion of carbon dioxide. This constitutes the driving force for generating motion, which is solely due to the respiration of leaves by photosynthesis. The rate of gas evolution can be fine‐tuned by changing the light intensity and the leaf size, allowing ultimately to control the motility of objects with dimensions ranging from the millimeter to the micrometer scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metastable Mn 5 O 8 phase stabilized via hydrothermal assisted calcination process. • pH plays a significant role in stabilizing the Mn 5 O 8 phase. • Controlled morphological synthesis of Mn 5 O 8 done via varying precipitating agents. • NaOH, ammonia, oleylamine stabilize Mn 5 O 8 phase while the oxalate route forms Mn 2 O 3. • Mn 5 O 8 nanoplates exhibit low η 10 @270 mV vs. hexagonal nanoplates, nanorods of Mn 5 O 8. The stabilization of manganese oxide nanostructures with tunable oxidation states and morphologies is crucial for regulating catalytic properties. In this study, we aim to stabilize the metastable monoclinic Mn 5 O 8 phase and control the morphology of the Mn 5 O 8 nanostructures using a hydrothermal assisted calcination process in the presence of different precipitating agents. Raman experiments confirmed that the interaction of aqueous Mn2+ salts with different precipitating agents such as NaOH, ammonia, and oleylamine, resulted in the formation of Mn 5 O 8. On the other hand, the precipitation of Mn2+ salt using diammonium oxalate monohydrate as a precipitating agent led to complete oxidation forming Mn 2 O 3. Detailed phase and microstructural analyses were conducted using PXRD, XPS, and FESEM. The analyses revealed the formation of the monoclinic Mn 5 O 8 phase with various morphologies, including hexagonal nanoplates, nanorods, and random nanoplates, when using NaOH, ammonia, and oleylamine as precipitating agents. The synthesized Mn 5 O 8 phase was deposited onto an iron sheet as a substrate. Furthermore, we demonstrated the effect of the structure, morphology, and size of the Mn 5 O 8 material on O 2 evolution activity. The catalytic performance of irregularly shaped Mn 5 O 8 nanoplates showed significantly lower η 10 (270 mV) and η 50 (350 mV) compared to Mn 5 O 8 hexagonal nanoplates, Mn 5 O 8 nanorods, and Mn 2 O 3 nanostructure. Additionally, an insight into the catalytic performance was investigated in detail by evaluating electrochemical active sites, impedance spectroscopy, and hydrophilicity/hydrophobicity of the Mn 5 O 8 material. [ABSTRACT FROM AUTHOR]

Water splitting is an emerging domain in the sustainable energy system. In this study a half‐sandwich [Ru(η6‐benzene)(hdm)]BF4 [Ru‐hdm] complex (hdm=hydroxydi(pyridine‐2‐yl)methanolate) has been synthesized and characterized through various spectroscopic techniques. The complex [Ru‐hdm] has been employed to investigate the activity towards electrochemical and chemical water oxidation. Efficient generation of O2 through chemical and electrochemical water oxidation (98 % Faradaic efficiency) in deionized water was observed. The formation of insoluble particles of [RuVI=O] and [RuIV=O] species in the reaction mixture and a coating over the surface of the silicone rubber septum has been noticed. The kinetics of chemical water oxidation reveals the 1st order dependency on CAN and catalyst concentration. [ABSTRACT FROM AUTHOR]

• Optimal nominal Ru content of 30% is found for the stability of Ti/RuO 2 -Sb 2 O 5 -SnO 2 for oxygen evolution. • The service lives at the optimal nominal Ru content can be 8 and >22 times longer than any types of RuO 2 -based electrodes reported previously at 25 and 70 °C, respectively. • The excellent stability is attributed to the homogeneous intermixture of RuO 2 , SnO 2 and Sb 2 O 5 resulting a smooth and compact surface suppressing the dissolution of RuO 2. • The RuO 2 -Sb 2 O 5 -SnO 2 electrodes with 50 and 75% Ru nominally exhibit higher activity and stability than pure RuO 2 due to the proper amounts of Sn and Sb doped into the coating layer. • The optimal Ru content would depend on the balanced effect between electrochemical stability and activity for O 2 evolution, as well as cost for specific applications. The effects of ruthenium content on Ti/RuO 2 -Sb 2 O 5 -SnO 2 anodes are investigated in terms of catalytic activity and stability for oxygen evolution. The best electrochemical stability appears at nominal Ru content around 30%, giving average accelerated lives of 419 and 165 h at 25 and 70 °C, respectively, under the current density of 500 mA cm−2 in 3 M H 2 SO 4 solution. These values are respectively ~8 and >22 times longer than any types of RuO 2 -based electrodes reported previously. The electrocatalytic activity of Ti/RuO 2 -Sb 2 O 5 -SnO 2 anodes is found to increase with nominal Ru content approaching 75%. The physicochemical and electrochemical analyses reveal that the homogeneous intermixture of RuO 2 , SnO 2 and Sb 2 O 5 with a smooth and compact surface decreases the dissolution rate of RuO 2 , leading to a significant improvement on the electrode service life. Despite the numerous pores and cracks found in the coating, Ti/RuO 2 -Sb 2 O 5 -SnO 2 anode with a nominal Ru content of 75% exhibits better electrocatalytic performance for O 2 evolution, which is attributed to more active RuO 2 sites exposed to electrolyte. Therefore, the existence of the optimal Ru content for Ti/RuO 2 -Sb 2 O 5 -SnO 2 is the balanced effect between electrochemical stability and activity for O 2 evolution, as well as cost for specific applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Since the first great oxygenation event, photosynthetic microorganisms have continuously shaped the Earth’s atmosphere. Studying biological mechanisms involved in the interaction between microalgae and cyanobacteria with the Earth’s atmosphere requires the monitoring of gas exchange. Membrane inlet mass spectrometry (MIMS) has been developed in the early 1960s to study gas exchange mechanisms of photosynthetic cells. It has since played an important role in investigating various cellular processes that involve gaseous compounds (O2, CO2, NO, or H2) and in characterizing enzymatic activities in vitro or in vivo. With the development of affordable mass spectrometers, MIMS is gaining wide popularity and is now used by an increasing number of laboratories. However, it still requires an important theory and practical considerations to be used. Here, we provide a practical guide describing the current technical basis of a MIMS setup and the general principles of data processing. We further review how MIMS can be used to study various aspects of algal research and discuss how MIMS will be useful in addressing future scientific challenges.

Although n-butanol (BuOH) is an ideal fuel because of its superior physical properties, it has toxicity to microbes. Previously, a Synechococcus elongatus PCC 7942 derivative strain that produces BuOH from CO 2 was developed by introducing six heterologous genes (BUOH-SE strain). To identify the bottleneck in BuOH production, the effects of BuOH production and its toxicity on central metabolism and the photosystem were investigated. Parental (WT) and BUOH-SE strains were cultured under autotrophic conditions. Consistent with the results of a previous study, BuOH production was observed only in the BUOH-SE strain. Isotopically non-stationary 13 C-metabolic flux analysis revealed that the CO 2 fixation rate was much larger than the BuOH production rate in the BUOH-SE strain (1.70 vs 0.03 mmol gDCW -1 h -1 ), implying that the carbon flow for BuOH biosynthesis was less affected by the entire flux distribution. No large difference was observed in the flux of metabolism between the WT and BUOH-SE strains. Contrastingly, in the photosystem, the chlorophyll content and maximum O 2 evolution rate per dry cell weight of the BUOH-SE strain were decreased to 81% and 43% of the WT strain, respectively. Target proteome analysis revealed that the amounts of some proteins related to antennae (ApcA, ApcD, ApcE, and CpcC), photosystem II (PsbB, PsbU, and Psb28-2), and cytochrome b 6 f complex (PetB and PetC) in photosystems decreased in the BUOH-SE strain. The activation of photosynthesis would be a novel approach for further enhancing BuOH production in S. elongatus PCC 7942.

This chapter compares two different techniques for monitoring photosynthetic O 2 production; the wide-spread Clark-type O 2 electrode and the more sophisticated membrane inlet mass spectrometry (MIMS) technique. We describe how a simple membrane inlet for MIMS can be made out of a commercial Clark-type cell and outline the advantages and drawbacks of the two techniques to guide researchers in deciding which method to use. Protocols and examples are given for measuring O 2 evolution rates and for determining the number of chlorophyll molecules per active photosystem II reaction center., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Production of hydrogen and oxygen from water splitting reaction under visible light is a simple method for conversion of solar-to-hydrogen energy and it is a hopeful clean and renewable method for H 2 fuel generation. However, there is still a lack of potential materials with significant activity under visible light. Because of safety, chemical inertness, low cost, stability and other characteristics, transition metal oxide semiconductors have been widely applied as photocatalysts for hydrogen generation. Albeit, wide usage of semiconductor photocatalysts were prevented by its inability to exploit solar energy of visible region. Here we show synthesis of a nano-sized mixed metal oxide (MMO) Ca 3 MnO 6 through wet-chemistry methods such as co-precipitation, ultrasonic, microwave, reflux, and hydrothermal methods. The nano-sized Ca 3 MnO 6 has initially selected based on morphology and respective particle diameters. The selected sample shows a well-defined single crystal, free from any impurities, complete structural formation, and a band gap energy (E g) of around 5.3 eV. The best product synthesized in ultrasonic method which shows the best morphology, purity and the highest efficiency for splitting of water to hydrogen and oxygen. Irrespective of preparation methods and morphologies, all samples split water into hydrogen and oxygen, as confirmed from their respective photocatalytic analysis. When the selected sample combined with (NH 4) 2 Ce(NO 3) 6 , the single-crystal Ca 3 MnO 6 nanoparticles split water into hydrogen and oxygen more efficiently under visible light. Our findings demonstrate the importance of nanostructured Ca 3 MnO 6 single-crystal photocatalysts in solar water splitting. • Multidisciplinary techniques based wet-chemistry method utilize for production of CaMn 3 O 6 nanocatalysts. • Various preparation techniques foster particles formation with different morphologies. • CaMn 3 O 6 nanocatalysts well growth via co-precipitation technique. • Unique morphologies, properties and crystalline texture support its catalytic activities. • Presence of redox species like Mn enhance O 2 evolution performances. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hierarchical TiO 2 nanotube with uniform carbon coatings is synthesized successfully. • The TiO 2 /C hierarchical nanotube exhibits the best photocatalytic activity under full solar spectrum light irradiation. • The incorporation of visible/NIR light active carbon coating with UV light responsive TiO 2 promote solar utilization. • The hierarchical nanotube can generate multiple reflections of incident light to promote an efficient light harvesting. • The generated carbon coatings on the surface of TiO 2 facilitate electron-hole separation. Abstract Smart architectures of TiO 2 are attracting increasing attention due to their outstanding properties in a broad range of fields. Herein, hierarchical TiO 2 nanotube with uniform carbon coatings is synthesized as the full solar spectrum photocatalytic materials for O 2 evolution by a facile solvothermal method. This unique structure consists of an interstitial hollow spaces and a functional nanotube shell assembled from two-dimensional (2D) nanosheets. By adjusting the types of solvents and reaction time, the morphologies of TiO 2 /C composites can be tuned to nanoparticles, nanorods, or hierarchical nanotubes. Among these morphologies, the TiO 2 / C hierarchical nanotube exhibits the best photocatalytic activity and favorable stability toward oxygen evolution from water oxidation under full solar spectrum light irradiation. The reason is attributed to the desirable incorporation of visible/near-infrared (NIR) light active carbon coating with UV light responsive TiO 2 for promoted solar energy utilization. Besides, the solvothermal step leads to hierarchical nanotube structures which can generate multiple reflections of incident light so as to promote an efficient light harvesting due to an enhanced specific surface area (244.4 m2 g−1) and light scattering ability. Moreover, the generated carbon coatings on the surface of TiO 2 facilitate electron-hole separation. [ABSTRACT FROM AUTHOR]

• A novel g-C 3 N 4 with Na, o co-doping and cyano groups photocatalyst was successfully prepared. • NOC CN catalyst had stronger oxidation capacity. • NOC CN exhibits a narrower band gap. • NOC CN exhibits boosted photocatalytic oxygen evolution without any co-catalyst. Tuning the electronic structure is fundamental to improve the optical character and redox ability of photocatalysts. Thus, in this article, g-C 3 N 4 with sodium and oxygen co-doping and cyano groups (NOC CN) was successfully synthesized by a brief one-step thermopolymerization. The results indicate that introduction of sodium and oxygen dopant and cyano groups bring a narrower band gap for NOC CN, adjust the overall electronic structure of NOC CN in the positive direction, and facilitate more efficient electron migration ability, which promoted NOC CN achieving photocatalytic water splitting oxygen evolution rate of 1.26 mmolh−1 g −1 without the assistance of any co-catalyst. Furthermore, DFT calculation and related experimental results was also combined to confirm the chemical structure of NOC CN. Obviously, this paper provides a feasible tactic to inflect the electronic construction of g-C 3 N 4 , improving its oxidizing ability. Na, O co-doping and cyano groups synergistically adjust the band structure of graphite carbon nitride for photocatalytic oxygen evolution without co-catalyst. [Display omitted]. [ABSTRACT FROM AUTHOR]

Keywords: gas exchange; photosynthesis; carbonic anhydrase; CO2 concentrating mechanism; O2 evolution; H2 production; microalgae; cyanobacteria EN gas exchange photosynthesis carbonic anhydrase CO2 concentrating mechanism O2 evolution H2 production microalgae cyanobacteria N.PAG N.PAG 3 12/26/20 20201222 NES 201222 In the original article, in the paragraph on the "Assessment of Photosynthetic Oxygen Exchange", we defined the O SB 2 sb uptake rate with a negative value when oxygen is consumed. While photosystem II (PSII) produces unlabeled O 2 from the photolysis of H 2 O, oxygen uptake mechanisms consume both 18 O-labeled and unlabeled O 2 (B) 16 O 2 and 18 O 2 concentrations measured in C. reinhardtii cells during dark-light transients. Gas exchange, photosynthesis, carbonic anhydrase, CO2 concentrating mechanism, O2 evolution, H2 production, microalgae, cyanobacteria. [Extracted from the article]

[Display omitted] • Pt/ZIF-67 was synthesized by the immobilization of ultrafine PtNPs at the surface of ZIF-67. • Pt/ZIF-67 shown superior catalytic activity in both H 2 and O 2 evolution. • The "on–off" switch for H 2 evolution from NH 3 BH 3 hydrolysis was developed. • NH 3 BH 3 and H 2 O 2 are deemed as an economic and safe H 2 resp. O 2 carrier for fuel cell. In spite of significant developments are accomplished in the exploration of H 2 and O 2 evolution upon water electrolysis/photolysis, this remains a challenge to design and develop ideal catalytic systems for this reaction and to isolate H 2 from H 2 -O 2 mixture with membranes. Herein, a series of ZIF-67-supported transition metal nanoparticles (TMNPs/ZIF-67), including Pt, Ir, Pd, Rh, Au and Ag, via immobilization of ultrafine TMNPs at the surface of ZIF-67, have been designed and developed for the selective H 2 generation from NH 3 BH 3 hydrolysis and O 2 evolution upon H 2 O 2 decomposition. In particular, the optimized nanocatalyst Pt/ZIF-67 presents the super-high catalytic property in the both H 2 evolution upon NH 3 BH 3 hydrolysis (689 mol(H 2)·mol Pt -1·min−1) and O 2 evolution upon H 2 O 2 decomposition (979 mol(O 2)·mol Pt -1·min−1) at 30 °C. Importantly, the selective "on–off" control for demand-based H 2 generation from NH 3 BH 3 hydrolysis was successfully realized by Zn2+/EDTA-2Na system. This highly efficient Pt/ZIF-67 proposed a new method for the promising potential application of ammonia borane and hydrogen peroxide as an economic and safe H 2 resp. O 2 carrier for fuel cell. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient synthesis of Magnetite@SiO 2 @TiO 2 -CoPcS nanocomposite. • Characterization of the nanocomposite using FT-IR, TG-DTG, SEM, FT-IR, VSM, EDS and XRD. • Magnetite@SiO 2 @TiO 2 -CoPcS nanocomposites utilized for photocatalytic oxygen evolution under visible irradiation. • Nanocomposite can be recovered and reused several times by magnetic separation without any. • Considerable changes in the catalytic activity. In the present study, magnetic photocatalysts, Magnetite@SiO 2 @TiO 2 -CoPcS (Mag@S@T-CoPcS) were synthesized, as a magnetic photocatalyst, and utilized for photocatalytic oxygen evolution under visible irradiation. Different methods were used to characterize the developed nanocomposites, such as Fourier transform infrared (FT-IR), energy-dispersive X-ray (EDX) spectroscopies, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). A vibrating sample magnetometer (VSM) was used for conducting magnetic measurements of the prepared nanocomposites, and the maximum saturation magnetization was obtained as 8 and 10 emu g−1 for Mag@S@T-CoPcS and Fe 3 O 4 @SiO 2 @TiO 2 (Mag@S@T) nanocomposites. The UV–Vis reflectance results revealed a bandgap of 1.7 eV for Mag@S@T-CoPcS nanocomposites. The amount of oxygen evolution for the Mag@S@T-CoPcS nanocomposite with different amounts of AgNO 3 as the electron acceptor was measured by an oxygen meter under blue light emitting diodes (LED) irradiation. The rate of oxygen evolution for the Mag@S@T-CoPcS nanocomposite in the presence of AgNO 3 0.05 M was 2.4 mg L−1 being higher than the oxygen amount produced with Mag@S@T. It was possible to easily recover the involved magnetic catalyst after three cycles by an external magnetic field. [ABSTRACT FROM AUTHOR]