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Economical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts with high activity aimed at replacing precious metal catalysts for rechargeable zinc-air batteries (ZABs) must be developed. In this study, a multiple hierarchical-structural material is developed using a facile dielectric barrier discharge (DBD) plasma surface treatment, solvothermal reaction, and high-temperature carbonization strategy. This strategy allows for the construction of nanosheets using nitrogen-doped carbon (NC) material-encapsulated ternary CoNiFe alloy nanoparticles (NPs) on a network of NC nanotubes (NCNTs), denoted as CoNiFe-NC@p-NCNTs. Precisely, the presence of abundant CoNiFe alloy NPs and the formation of M-N-C active sites created by transition metals (cobalt, nickel, and iron) coupled with NC can provide superior OER/ORR bifunctional properties. Moreover, the prepared NC layers with a multilevel pore structure contribute to a larger specific surface area, exposing numerous active sites and enhancing the uniformity of electron and mass movement. The CoNiFe 0.08 -NC@p-NCNTs show remarkable dual functionality for electrochemical oxygen reactions (ORR half-wave potential of 0.811 V, limiting current density of 5.73 mA cm -2 measured with a rotating disk electrode at a rotation speed of 1600 rpm, and OER overpotential of 351 mV at 10 mA cm -2 ), which demonstrates similar ORR performance to 20 wt% Pt/C and better OER performance than the commercial RuO 2 . A liquid ZAB prepared using the proposed material has excellent bifunctionality with an open-circuit voltage of 1.450 V and long-term cycling stability of 230 h@10 mA cm -2 ., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This work reports a strategy that integrates the carbon nanotube (CNT) supporting, ultrathin carbon coating and oxygen defect generation to fabricate the RuO 2 based catalysts toward the pH-universal hydrogen evolution reaction (HER) with high efficiencies. Specifically, the CNT supported RuO 2 nanoparticles with ultrathin carbon loricae and rich oxygen vacancies at the surface (C@OV-RuO 2 /CNTs-325) have been synthesized. The C@OV-RuO 2 /CNTs-325 shows superior activities and excellent durability for the HER. It only requires overpotentials of 36.1, 18.0, and 19.3 mV to deliver -10 mA cm -2 in the acidic, neutral, and alkaline media, respectively. Its HER activities are comparable to that of the Pt/C in the acidic media but higher than those of the Pt/C in the neutral and alkaline media. The C@OV-RuO 2 /CNTs-325 shows excellent HER durability with no activity losses for > 500 h in the acidic, neutral or alkaline media at -250 mA cm -2 . The density-functional-theory calculations indicate that the CNT supporting, the carbon coating, and the OVs can modulate the d-band centers of Ru, increasing the HER activities of C@OV-RuO 2 /CNTs-325, and stabilize the Ru atoms in the catalyst, increasing the durability of the C@OV-RuO 2 /CNTs-325. More interestingly, the C@OV-RuO 2 /CNTs-325 shows great potential for practical applications toward overall seawater splitting., (© 2024 Wiley‐VCH GmbH.)

This work reports the use of defect engineering and carbon supporting to achieve metal-doped phosphides with high activities and stabilities for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline media. Specifically, the nitrogen-doped carbon nanofiber-supported Ni-doped CoP 3 with rich P defects (Pv·) on the carbon cloth (p-NiCoP/NCFs@CC) is synthesized through a plasma-assisted phosphorization method. The p-NiCoP/NCFs@CC is an efficient and stable catalyst for the HER and the OER. It only needs overpotentials of 107 and 306 mV to drive 100 mA cm -2 for the HER and the OER, respectively. Its catalytic activities are higher than those of other catalysts reported recently. The high activities of the p-NiCoP/NCFs@CC mainly arise from its peculiar structural features. The density functional theory calculation indicates that the Pv· richness, the Ni doping, and the carbon supporting can optimize the adsorption of the H atoms at the catalyst surface and promote the strong electronic couplings between the carbon nanofiber-supported p-NiCoP with the surface oxide layer formed during the OER process. This gives the p-NiCoP/NCFs@CC with the high activities for the HER and the OER. When used in alkaline water electrolyzers, the p-NiCoP/NCFs@CC shows the superior activity and excellent stability for overall water splitting., (© 2024. The Author(s).)

This work utilizes defect engineering, heterostructure, pyridine N-doping, and carbon supporting to enhance cobalt-nickel selenide microspheres' performance in the oxygen electrode reaction. Specifically, microspheres mainly composed of CoNiSe 2 and Co 9 Se 8 heterojunction rich in selenium vacancies (V Se· ) wrapped with nitrogen-doped carbon nanotubes (p-CoNiSe/NCNT@CC) are prepared by Ar/NH 3 radio frequency plasma etching technique. The synthesized p-CoNiSe/NCNT@CC shows high oxygen reduction reaction (ORR) performance (half-wave potential (E 1/2 ) = 0.878 V and limiting current density (J L ) = 21.88 mA cm -2 ). The J L exceeds the 20 wt% Pt/C (19.34 mA cm -2 ) and the E 1/2 is close to the 20 wt% Pt/C (0.881 V). It also possesses excellent oxygen evolution reaction (OER) performance (overpotential of 324 mV@10 mA cm -2 ), which even exceeds that of the commercial RuO 2 (427 mV@10 mA cm -2 ). The density functional theory calculation indicates that the enhancement of ORR performance is attributed to the synergistic effect of plasma-induced V Se· and the CoNiSe 2 -Co 9 Se 8 heterojunction. The p-CoNiSe/NCNT@CC electrode assembled Zinc-air batteries (ZABs) show a peak power density of 138.29 mW cm -2 , outperforming the 20 wt% Pt/C+RuO 2 (73.9 mW cm -2 ) and other recently reported catalysts. Furthermore, all-solid-state ZAB delivers a high peak power density of 64.83 mW cm -2 and ultra-robust cycling stability even under bending., (© 2024 Wiley‐VCH GmbH.)

The optimization of metal-support interactions is used to fabricate noble metal-based nanoclusters with high activity for hydrogen evolution reaction (HER) in acid media. Specifically, the oxygen-defective Mn 3 O 4 nanosheets supported Pt nanoclusters of ≈1.71 nm in diameter (Pt/V·-Mn 3 O 4 NSs) are synthesized through the controlled solvothermal reaction. The Pt/V·-Mn 3 O 4 NSs show a superior activity and excellent stability for the HER in the acidic media. They only require an overpotential of 19 mV to drive -10 mA cm -2 and show negligible activity loss at -10 and -250 mA cm -2 for >200 and >60 h, respectively. Their Pt mass activity is 12.4 times higher than that of the Pt/C and even higher than those of many single-atom based Pt catalysts. DFT calculations show that their high HER activity arises mainly from the strong metal-support interaction between Pt and Mn 3 O 4 . It can facilitate the charge transfer from Mn 3 O 4 to Pt, optimizing the H adsorption on the catalyst surface and promoting the evolution of H 2 through the Volmer-Tafel mechanism. The oxygen vacancies in the V·-Mn 3 O 4 NSs are found to be inconducive to the high activity of the Pt/V·-Mn 3 O 4 NSs, highlighting the great importance to reduce the vacancy levels in V·-Mn 3 O 4 NSs., (© 2024 Wiley‐VCH GmbH.)

Environmental pollution caused by persistent organic pollutants has imposed big threats to the health of human and ecological systems. The development of efficient methods to effectively degrade and remove these persistent organic pollutants is therefore of paramount importance. Photocatalytic persulfate-based advanced oxidation technologies (PS-AOTs), which depend on the highly reactive SO 4 - radicals generated by the activation of PS to degrade persistent organic pollutants, have shown great promise. This work discusses the application and modification strategies of common photocatalysts in photocatalytic PS-AOTs, and compares the degradation performance of different catalysts for pollutants. Furthermore, essential elements impacting photocatalytic PS-AOTs are discussed, including the water matrix, reaction process mechanism, pollutant degradation pathway, singlet oxygen generation, and potential PS hazards. Finally, the existing issues and future challenges of photocatalytic PS-AOTs are summarized and prospected to encourage their practical application. In particular, by providing new insights into the PS-AOTs, this review sheds light on the opportunities and challenges for the development of photocatalysts with advanced features for the PS-AOTs, which will be of great interests to promote better fundamental understanding of the PS-AOTs and their practical applications., (© 2024 Wiley-VCH GmbH.)

Nanocomposite represents the backbone of many industrial fabrication applications and exerts a substantial social impact. Among these composites, metal nanostructures are often employed as the active constituents, thanks to their various chemical and physical properties, which offer the ability to tune the application scenarios in thermal management, energy storage, and biostable materials, respectively. Nanocellulose, as an emerging polymer substrate, possesses unique properties of abundance, mechanical flexibility, environmental friendliness, and biocompatibility. Based on the combination of flexible nanocellulose with specific metal fillers, the essential parameters involving mechanical strength, flexibility, anisotropic thermal resistance, and conductivity can be enhanced. Nowadays, the approach has found extensive applications in thermal management, energy storage, biostable electronic materials, and piezoelectric devices. Therefore, it is essential to thoroughly correlate cellulose nanocomposites' properties with different metallic fillers. This review summarizes the extraction of nanocellulose and preparation of metal modified cellulose nanocomposites, including their wide and particular applications in modern advanced devices. Moreover, we also discuss the challenges in the synthesis, the emerging designs, and unique structures, promising directions for future research. We wish this review can give a valuable overview of the unique combination and inspire the research directions of the multifunctional nanocomposites using proper cellulose and metallic fillers., (© 2024 Wiley-VCH GmbH.)

The development of cost-effective catalysts for oxygen evolution reaction (OER) in acidic media is of paramount importance. This work reports that Sr-doped solid solution structural ultrafine IrMnO 2 nanoparticles (NPs) (≈1.56 nm) on the carbon nanotubes (Sr-IrMnO 2 /CNTs) are efficient catalysts for the acidic OER. Even with the Ir use dosage 3.5 times lower than that of the commercial IrO 2 , the Sr-IrMnO 2 /CNTs only need an overpotential of 236.0 mV to drive 10.0 mA cm -2 and show outstanding stability for >400.0 h. Its Ir mass activity is 39.6 times higher than that of the IrO 2 at 1.53 V. The solid solution and Sr-doping structure of Sr-IrMnO 2 are the main origin of the high catalytic activity and excellent stability of the Sr-IrMnO 2 /CNTs. The density function theory calculations indicate that the solid solution structure can promote strong electronic coupling between Ir and Mn, lowering the energy barrier of the OER rate-determining step. The Sr-doping can enhance the stability of Ir against the chemical corrosion and demetallation. Water electrolyzers and proton exchange membrane water electrolyzers assembled with the Sr-IrMnO 2 /CNTs show superb performance and excellent durability in the acid media., (© 2023 Wiley‐VCH GmbH.)

The carbon nanotubes (CNTs) supported amorphous Sb doped substoichiometric tin dulfide (Sb─SnS x ) with a carbon coating (the C/Sb─SnS x @CNTs-500) is reported to be an efficient anode material for K + storage. The formation of the C/Sb─SnS x @CNTs-500 is simply achieved through the thermally induced desulfurization of tin sulfide via a controlled annealing of the C/Sb─SnS 2 @CNTs at 500 °C. When used for the K + storage, it can deliver stable reversible capacities of 406.5, 305.7, and 238.4 mAh g -1 at 0.1, 1.0, and 2.0 A g -1 , respectively, and shows no capacity drops when potassiated/depotassiated at 1.0 and 2.0 A g -1 for >3000 and 2400 cycles, respectively. Even at 10, 20, and 30 A g -1 , it can still deliver stable reversible capacities of 138.5, 85.1, and 73.8 mAh g -1 , respectively. The unique structure, which combines the advantageous features of carbon integration/coating, metal doping, and desulfurization-induced amorphous structure, is the main origin of the high performance of the C/Sb─SnS x @CNTs-500. Specifically, the carbon integration/coating can increase the electric conductivity and stability of the C/Sb─SnS x @CNTs-500. The density function theory calculation indicates that the Sb doping and the desulfurization can facilitate the potassiation and increase the electric conductivity of Sb─SnS x . Additionally, the desulfurization can increase the K + diffusivity in Sb─SnS x ., (© 2023 Wiley-VCH GmbH.)

The development of sodium-ion battery (SIB) anodes is still hindered by their rapid capacity decay and poor rate capabilities. Although there have been some new materials that can be used to fabricate stable anodes, SIBs are still far from wide applications. Strategies like nanostructure construction and material modification have been used to prepare more robust SIB anodes. Among all the design strategies, the hollow structure design is a promising method in the development of advanced anode materials. In the past decade, research efforts have been devoted to modifying the synthetic route, the type of templates, and the interior structure of hollow structures with high capacity and stability. A brief introduction is made to the main material systems and classifications of hollow structural materials first. Then different morphologies of hollow structural materials for SIB anodes from the latest reports are discussed, including nanoboxes, nanospheres, yolk shells, nanotubes, and other more complex shapes. The most used templates for the synthesis of hollow structrual materials are covered and the perspectives are highlighted at the end. This review offers a comprehensive discussion of the synthesis of hollow structural materials for SIB anodes, which could be potentially of use to research areas involving hollow materials design for batteries., (© 2023 The Chemical Society of Japan & Wiley-VCH GmbH.)

Plasma treatment and reduction are used to synthesize Pt nanoparticles (NPs) on nitrogen-doped carbon nanotubes (p-Pt/p-NCNT) with a low Pt content. In particular, the plasma treatment is used to treat the NCNT to give it with more surface defects, facilitating a better growth of the Pt NPs, while the plasma reduction produces the Pt NPs with a reduced fraction of the surface atoms at the high oxidation states, increasing the catalytic activities of the p-Pt@p-NCNT. Even at the low Pt content (7.8 wt.%), the p-Pt@p-NCNT shows superior catalytic activities and good stabilities for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The density functional theory (DFT) calculations indicate that the defects generated in the plasma treatment can help the growth of the Pt NPs on the NCNTs, leading to the stronger electronic coupling between Pt and NCNT and the increased stability of the catalyst. The plasma reduction can give the Pt NPs with optimized surface oxidation states, decreasing the energy barriers of the rate-determining steps for MOR and ORR. When used as the anode and cathode catalysts for the direct methanol fuel cells (DMFCs), the p-Pt@p-NCNT exhibits a higher maximum power density of 81.9 mW cm -2  at 80 °C and shows good durability., (© 2023 Wiley-VCH GmbH.)

Developing high-efficient, good-durability, and low-cost bifunctional non-precious metal catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is urgent and significant for promoting the practical rechargeable zinc-air batteries (RZABs). Herein, N-doped carbon coated Co/FeCo@Fe(Co) 3 O 4 heterojunction rich in oxygen vacancies derived from metal-organic frameworks (MOFs) is successfully constructed by O 2 plasma treatment. The phase transition of Co/FeCo to FeCo oxide (Fe 3 O 4 /Co 3 O 4 ) mainly occurs on the surface of nanoparticles (NPs) during the O 2 plasma treatment, which can form rich oxygen vacancies simultaneously. The fabricated catalyst P-Co 3 Fe 1 /NC-700-10 with optimal O 2 plasma treatment time of 10 min can reduce the potential gap between the OER and ORR to 760 mV, which is much lower than commercial 20% Pt/C + RuO 2 (910 mV). Density functional theory (DFT) calculation indicates that the synergistic coupling between Co/FeCo alloy NPs and FeCo oxide layer can promote the ORR/OER performance. Both liquid electrolyte RZAB and flexible all-solid-state RZAB using P-Co 3 Fe 1 /NC-700-10 as the air-cathode catalyst display high power density, specific capacity and excellent stability. This work provides an effective idea for the development of high performance bifunctional electrocatalyst and the application of RZABs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Direct methanol fuel cells (DMFCs) have been the focus of future research because of their simple structure, abundant fuel sources, high energy conversion efficiency and low cost. Among the components in DMFC, the activity and stability of the cathode catalyst is the key to the performance and lifetime of the DMFCs. Oxygen reduction reaction (ORR) is an important electrode reaction on DMFC cathode. It is known that Pt is widely used in the fabrication of ORR catalysts, but the limited earth storage of Pt and its high price limit the use of Pt-based commercial catalysts in DMFCs. To overcome these problems, advances have been made on new low Pt-based catalysts and Pt-free catalysts in recent years. In this article, the development of novel ORR catalysts and the carbon supports is reviewed and discussed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Qin, Tian, Wang, Jiang and Jiang.)

This work reports an amorphization and partial desulfurization method to improve the performance of sulfide-based materials for Na + storage. Specifically, the polypyrrole derived carbon coated amorphous substoichiometric tin sulfide supported on aminated carbon nanotubes (PPY-C@SnS x /ACNTs) with amorphized and substoichiometric tin sulfide (SnS x ) is synthesized by simply thermal annealing the PPY-C@SnS 2 /ACNTs. The PPY-C@SnS x /ACNTs shows stable reversible capacities of 410.2 mAh g -1 for Na + storage at 0.1 A g -1 and excellent rate capacities of 270.2, 235.5, 217.4, and 210.0 mAh g -1 at 5.0, 10.0, 20.0, and 30.0 A g -1 , respectively. Nearly zero drops on the reversible capacities can be observed when it is sodiated/desodiated at 2.0, 5.0, and 10.0 A g -1 for up to 1000, 6500, 8000 cycles, respectively. Its outstanding rate capacities and degradation-free cycling stabilities mainly arise from the amorphized and substoichiometric structure of SnS x , which improve the reversible capacities and Na + diffusivities of the PPY-C@SnS x /ACNTs. The density functional theory (DFT) calculations indicate that the partial desulfurization can improve the electric conductivity and promote the sodiation/desodiation of SnS x . It explains why the PPY-C@SnS x /ACNTs can exhibit high performance for Na + storage well., (© 2022 Wiley-VCH GmbH.)

This work reports a novel approach for the synthesis of FeCo alloy nanoparticles (NPs) embedded in the N,P-codoped carbon coated nitrogen-doped carbon nanotubes (NPC/FeCo@NCNTs). Specifically, the synthesis of NCNT is achieved by the calcination of graphene oxide-coated polystyrene spheres with Fe 3+ , Co 2+ and melamine adsorbed, during which graphene oxide is transformed into carbon nanotubes and simultaneously nitrogen is doped into the graphitic structure. The NPC/FeCo@NCNT is demonstrated to be an efficient and durable bifunctional catalyst for oxygen evolution (OER) and oxygen reduction reaction (ORR). It only needs an overpotential of 339.5 mV to deliver 10 mA cm -2 for OER and an onset potential of 0.92 V to drive ORR. Its bifunctional catalytic activities outperform those of the composite catalyst Pt/C + RuO 2 and most bifunctional catalysts reported. The experimental results and density functional theory calculations have demonstrated that the interplay between FeCo NPs and NCNT and the presence of N,P-codoped carbon structure play important roles in increasing the catalytic activities of the NPC/FeCo@NCNT. More impressively, the NPC/FeCo@NCNT can be used as the air-electrode catalyst, improving the performance of rechargeable liquid and flexible all-solid-state zinc-air batteries., Competing Interests: The authors declare no conflict of interest., (© 2021 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

In this work, density functional theory (DFT) calculations are performed to understand the origin of the regioselective C-H borylation of aromatics catalyzed by Co(i)/ iPr PNP and Ir(iii)/dtbpy (4,4-di- tert -butyl bipyridine). The calculation results indicate that for the Co(i)/ iPr PNP catalytic system, the undirected pathway is 2.9 kcal mol -1 more favoured over the directed pathway leading to ortho -to-fluorine selectivity. In contrast, for the Ir(iii)/dtbpy catalytic system, the directed pathway is 1.2 kcal mol -1 more favoured over the undirected pathway bringing about ortho -to-silyl selectivity. For Co(i)/ iPr PNP catalyzed borylation, the undirected pathway which involves steps of ortho -to-fluorine C-H oxidative addition, C-B reductive elimination, B-B oxidative addition, and B-H reductive elimination is favorable due to the electron deficient character of the ortho -to-fluorine C-H bond. For Ir(iii)/dtbpy catalyzed borylation, the directed pathway consisting of Si-H oxidative addition, B-H reductive elimination, C-H oxidative addition, B-B oxidative addition, C-B reductive elimination, Si-H reductive elimination is favored over the undirected pathway attributed to the directing effect of the hydrosilyl group. The favourable undirected pathway ( orth o-to-fluorine selectivity) for Co(i)/ iPr PNP catalyzed borylation and the favourable directed pathway ( ortho -to-silyl selectivity) for Ir(iii)/dtbpy catalyzed borylation could explain well the experimentally observed ortho -to-fluorine borylation of hydrosilyl substituted fluoroarenes with cobalt catalyst (J. V. Obligacion, M. J. Bezdek and P. J. Chirik, J. Am. Chem. Soc. , 2017, 139 , 2825-2832) and ortho -to-silyl selectivity with iridium catalyst (T. A. Boebel and J. F. Hartwig, J. Am. Chem. Soc. , 2008, 130 , 7534-7535)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Correction for 'Predictable spectroscopic properties of type-II ZnTe/CdSe nanocrystals and electron/hole quenching' by Tongqing Long et al., Phys. Chem. Chem. Phys., 2019, 21, 5824-5833.

The spectroscopic properties of core/shell structured ZnTe/CdSe nanocrystals (NCs) have been systematically studied. By varying the ZnTe core diameter and the CdSe shell thickness, the absorption onset and the photoluminescence peak position of the ZnTe/CdSe NCs can be readily tuned over a wide range. The theoretical model based on an effective mass approximation demonstrates that the ZnTe/CdSe NCs have type II carrier localization in which the photoexcited electrons and holes are spatially separated and confined in the shell and core, respectively. The energetics of the conduction and valence bands and the bandgaps of the ZnTe/CdSe NCs are accurately predicted. The photoluminescent experiments show that electron quenchers having a large energy difference between their reduction potential and the lowest conduction band edge of the ZnTe/CdSe nanocrystals can completely quench the luminescence. Electron acceptors having a reduction potential only slightly below the conduction band edge partially quench the photoluminescence of the nanocrystals. In this case, the extent of quenching depends upon the thickness of the shell and the energy difference. Despite the confinement of photoexcited holes in the core, the photoluminescence could be still quenched by adsorbed hole quenchers. The extent of hole quenching depends upon the core size, the shell thickness and the oxidation potential of the quenchers. Basically, an increase in the core size and the shell thickness may lead to a decrease in the extent of hole quenching. The work presented here is of great interest since it can be extended to understand the spectroscopic properties and photoluminescence quenching behaviors of other core/shell semiconductor NCs.

Core-shell Fe3O4@CoO NCs have been demonstrated to be efficient bifunctional catalysts for the oxygen reduction (ORR) and evolution (OER) reactions. Their activities are strongly shell thickness dependent. Specifically, nanocrystals with ∼2 monolayers of CoO can exhibit a potential difference of 0.794 V at OER and ORR current densities of 10 and -3 mA cm-2, respectively. This value is competitive to those of most active bifunctional catalysts reported. In addition, they are also used as the oxygen cathode for Zn-air batteries and can deliver a peak power density of 109 mW cm-2, much higher than that of the Pt-RuO2/C (88.1 mW cm-2).

A composite with a hierarchical structure consisting of nitrogen doped carbon nanosheets with the deposition of nitrogen doped carbon coated Co-CoO nanoparticles (Co-CoO@NC/NC) has been synthesized by a simple procedure involving the drying of the reaction mixture containing Co(NO 3 ) 2 , glucose, and urea and its subsequent calcination. The drying step is found to be necessary to obtain a sample with small and uniformly sized Co-CoO nanoparticles. The calcination temperature has a great effect on the catalytic activity of the final product. Specifically, the sample prepared at the calcination temperature of 800 °C shows better catalytic activity of the oxygen reduction reaction (ORR). Urea in the reaction mixture is crucial to obtain the sample with the uniformly sized Co-CoO nanoparticles and also plays an important role in improving the catalytic activity of the Co-CoO@NC/NC. Additionally, there exists a strong electronic interaction between the Co-CoO nanoparticles and the NC. Most interestingly, the Co-CoO@NC/NC is highly efficient for the ORR and can deliver an ORR onset potential of 0.961 V vs. RHE and a half-wave potential of 0.868 V vs. RHE. Both the onset and half-wave potentials are higher than those of most catalysts reported previously and even close to those of the commercial Pt/C (the ORR onset and half-wave potential of the Pt/C are 0.962 and 0.861 V vs. RHE, respectively). This, together with its high stability, strongly suggests that the Co-CoO@NC/NC could be used as an efficient catalyst for the ORR., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A facile template-free Ostwald ripening method is developed for the preparation of the reduced graphene oxide supported splode-like NiCo 2 O 4 hollow microsphere (SNHM/rGO). The graphene oxide used in the reaction mixture is found to play a crucial role in the formation of the SNHM/rGO. It promotes the formation of the NiCo-glycerol microspheres suitable for the Ostwald ripening to form the reduced graphene oxide supported hollow NiCo-glycerol microspheres, which is important for the subsequent calcination to form the SNHM/rGO. The obtained SNHM/rGO shows a great promise as the anode for lithium-ion batteries and can deliver a stable reversible capacity of 1048.1 mA h g -1 at the current density of 100 mA g -1 . The performance of the SNHM/rGO is much higher than that of most NiCo 2 O 4 -based materials reported previously, strongly suggesting that the SNHM/rGO could be used as the anode for practical applications. This is well supported by the higher performance of the LiCoO 2 //SNHM-rGO full cell. The excellent electrochemical performance can be attributed to the specific structure of the SNHM/rGO, which comprises the splode-like hollow NiCo 2 O 4 microspheres with the reduced graphene oxide integrated., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Natural biomolecules have potential as proton-conducting materials, in which the hydrogen-bond networks can facilitate proton transportation. Herein, a biomolecule/metal-organic framework (MOF) approach to develop hybrid proton-conductive membranes is reported. Single-strand DNA molecules are introduced into DNA@ZIF-8 membranes through a solid-confined conversion process. The DNA-threaded ZIF-8 membrane exhibits high proton conductivity of 3.40 × 10 -4 S cm -1 at 25 °C and the highest one ever reported of 0.17 S cm -1 at 75 °C, under 97% relatively humidity, attributed to the formed hydrogen-bond networks between the DNA molecules and the water molecules inside the cavities of the ZIF-8, but very low methanol permeability of 1.25 × 10 -8 cm 2 s -1 due to the small pore entrance of the DNA@ZIF-8 membranes. The selectivity of the DNA@ZIF-8 membrane is thus significantly higher than that of developed proton-exchange membranes for fuel cells. After assembling the DNA@ZIF-8 hybrid membrane into direct methanol fuel cells, it exhibits a power density of 9.87 mW cm -2 . This is the first MOF-based proton-conductivity membrane used for direct methanol fuel cells, providing bright promise for such hybrid membranes in this application., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO 3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112. The sulfonated graphitic structure of the SHGOs is believed to be one of the crucial factors resulting in the higher performance of the SPEEK/SHGO membrane, since it could increase the local density of the -SO 3 H groups in the membrane and induce a strong interfacial interaction between SHGO and the SPEEK matrix, which improve the proton conductivity and lower the swelling ratio of the membrane, respectively. Additionally, the proton conductivity of the membrane could be further enhanced by the presence of the holes in the graphitic planes of the SHGOs, since it provides an additional channel for transport of the protons. When used, direct methanol fuel cell with the SPEEK/SHGO membrane is found to exhibit much higher performance than that with Nafion 112, suggesting potential use of the SPEEK/SHGO membrane as the PEMs.

Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co(2+) ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc.

Boron and nitrogen codoped hollow graphene microspheres (NBGHSs), synthesized from a simple template sacrificing method, have been employed as an electrocatalyst for the oxygen reduction reaction (ORR). Because of their specific hollow structure that consists of boron and nitrogen codoped graphene, the NBGHSs can exhibit even high electrocatalytic activity toward ORR than the commercial JM Pt/C 40 wt %. This, along with their higher stability, makes the NBGHSs particularly attractive as the electrocatalyst for the ORR with great potential to replace the commonly used noble-metal-based catalysts.

Nitrogen-doped holey graphene hollow microspheres (NHGHSs), synthesized through a template sacrificing method, were utilized as an anode material for lithium ion batteries (LIBs). Because of their specific microspherical hollow structure comprising nitrogen-doped holey graphene (NHG), the NHGHSs can exhibit reversible capacities of ∼ 1563 mAh g(-1) at a low rate of 0.5 C and ∼ 254 mAh g(-1) at a high rate of 20 C, which are significantly higher than the discharge capacity of the pristine graphene and other graphene-based carbonaceous materials. These, along with their good cycling stability, clearly demonstrate the great potential of using the NHGHSs as the anode material for LIBs of both high energy and power densities. We believe that the high specific surface area, holey structure of nitrogen-doped graphene, specific microspherical hollow structure, and increased interlayer spacing between the NHG nanosheets in their hollow walls are the main origins of their high electrochemical performance.

The dynamics of biexcitons in CdSe nanoparticles are examined as a function of the magnitudes of internal electric fields. We show that the presence of strong internal fields results in rapid Auger recombination. The strengths of the electric fields and hence the Auger recombination rates are controlled in several different ways: specifically, by varying the dielectric constant of the surrounding solvent, by changing the particle surface stoichiometry and hence the magnitude of surface charges, and by inducing a piezoelectric field through the deposition of a lattice-mismatched shell material. Auger recombination is a momentum forbidden process. Fourier transformation of calculated spatial wave functions shows that higher conduction band states have large momentum components that relax the momentum conservation constraints. Relative Auger recombination times depend upon the extent to which the internal electric fields mix conduction band levels, which is easily calculated. Comparison with calculations of valence band states suggests that the excited particle in biexciton Auger recombination is the other electron. The experimental results can therefore be understood in terms of mixing of higher conduction band states with the lowest state from which recombination occurs.

The dynamics of the CdSe nanorod synthesis reaction have been studied, giving attention to the kinetics of magic-sized clusters (MSCs) that form as intermediates in the overall reaction. The MSCs have a distinct absorption peak, and the kinetics of this peak give insight into the overall reaction mechanism. In these studies, the reaction mixture consists primarily of Cd(phosphonate)(2) and trioctyl phosphine selenium in a solution of trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO). We find that the rate at which precursors react to form CdSe monomers and the rates at which monomers react to form nanoparticles can be varied by changing the chemistry of the reaction mixture. Decreasing the TOP concentration decreases the extent to which selenium is bound, both in the precursors and on the particles' surfaces, and thereby increases both the precursor to monomer and monomer to particle reaction rates. Decreasing the phosphonate concentration decreases the extent to which phosphonate binds cadmium in the precursors and on the surface of the nanoparticles, also increasing the rates of both reactions. This is also accomplished by the addition of inorganic acids which protonate the phosphonates. The presence of inorganic acids (impurities) is the primary reason that the overall synthesis reaction is faster in solutions made with technical grade rather than purified TOPO. The TOP and phosphonic acid concentrations are coupled because excess phosphonic acids react with TOP, forming TOPO and less strongly binding species, specifically phosphinic acids, phosphine oxides, and phosphines.

A mathematical model has been developed to compute the spectroscopic properties of fluorescence systems with multiple Förster transfer pairs in a homogeneous 3-dimensional matrix. This model is based on Förster energy transfer theory and needs only a limited number of parameters which depend only on the properties of the individual dyes and their pair-wise interactions. Yet, the model allows the accurate prediction on the fluorescence properties of systems comprising mutual Förster transfer between three dyes. The model is compared to an experimental system composed of reverse micelles and water soluble dyes. Although the experimental system might include additional effects that may influence the fluorescence properties (e.g. adsorption to the micelle walls, aggregation of the dyes) the agreement between the mathematical model and the experimental system is reasonably good.

In this work, we investigate the catalytic properties of silver nanoparticles supported on silica spheres. The technique to support silver particles on silica spheres effectively avoids flocculation of nanosized colloidal metal particles during a catalytic process in the solution, which allows one to carry out the successful catalytic reduction of dyes. The effects of electrolytes and surfactants on the catalytic properties of silver particles on silica have been investigated. It is found that the presence of surfactants depresses the catalytic activity of the silver particles to some extent by inhibiting the adsorption of reactants onto the surface of the particles. Electrolytes either increase the migration rate of reactants in the solution resulting in an increase in the catalytic reaction rate or inhibit the adsorption of reactants onto the surface of the silver particles leading to a loss in the activity of the metal particles.