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Owing to a large band gap and high surface energy determined via theoretical calculation, anatase TiO2 with dominant (211) facets can be expected to serve as one of the candidates for inorganic photoanode materials. Unfortunately, high-energy (211) surfaces containing four- and five-coordinated Ti atoms usually diminish rapidly during the crystal growth by a thermal process as a result of the minimization of surface energy. Here we report a successful preparation of an anatase TiO2 photoanode with dominant (211) facets on various substrates by magnetron sputtering technology. The proposed formation mechanism of (211) facets is derived from the competition between high-energy ion impinging and thermodynamics in the deposition process. The TiO2 photoanode with over 1 μm thickness yields a record charge-separation efficiency of ∼54.4% at 0.46 V versus the reversible hydrogen electrode, corresponding to a photocurrent density of ∼0.32 mA cm−2. The photogenerated charge carriers are directionally separated within the crystal grains by the internal magnetic field and quickly transported on the (211) surfaces with unsaturated coordination sites. Most importantly, we find that the photoanode simultaneously integrates flexible, hard and lubricant effects into photoelectrochemical behaviors, leading to long-term stable operation (over 1100 h), good durability with a low wear rate, and facile bendability (similar performance before and after bending). We also fabricate a large-area (10 × 10 cm2) photoanode and use it in an unbiased photoelectrochemical device, further suggesting its scaling and practical potential. [ABSTRACT FROM AUTHOR]

Correction for 'Atomically dispersed cobalt on graphitic carbon nitride as a robust catalyst for selective oxidation of ethylbenzene by peroxymonosulfate' by Jiaquan Li et al., J. Mater. Chem. A, 2021, 9, 3029–3035, https://doi.org/10.1039/D0TA11503G. [ABSTRACT FROM AUTHOR]

Renewable energies from solar and wind power are playing an ever increasing role in meeting the tremendous global energy demand with substantially reduced carbon emissions; however, their intermittent nature poses a critical challenge for sustainability and practical applications. The capability of solid oxide cells (SOCs) to operate in both fuel cell and electrolysis modes makes them one of the most important candidates for efficient storage and regeneration of renewable energies. Here we present a critical review and prospects on the development of key fabrication techniques, e.g. wet infiltration, exsolution and direct assembly, for nanostructured electrodes, one of the most critical issues affecting the performance and stability of SOC technologies. The traits and challenges of these techniques are thoroughly discussed, with an aim to provide a critical guide for future design and development of more refined, high-performing nanostructured electrodes for SOCs. [ABSTRACT FROM AUTHOR]

Despite considerable progress in the field of sustainable ammonia technology, the low efficiency and yield have remained the main bottleneck in artificial nitrogen fixation under ambient conditions. In this work, an ultrathin carbon quantum dot modified hydrogenated mesoporous SrTiO3 heterostructure (CQDs/STO) has been developed as a bifunctional catalyst for enhanced nitrogen reduction. CQDs/STO exhibits a high photocatalytic activity and an ammonia yield of 143 μmol g−1 h−1 has been achieved without any sacrificial reagent, which is about 7 times that of STO nanoparticles. Furthermore, we demonstrate that CQDs/STO can be utilized as a bifunctional catalyst for cascade photoelectrochemical nitrogen reduction, resulting in a ∼50% increase in the ammonia yield. DFT calculations reveal that the synergy between SrTiO3 and CQDs has the capability for photocatalytic reduction of N2 with the O-vacancies in SrTiO3 playing a key role also as electrocatalytic centers. We believe that such a cascade catalytic system provides a new insight into designing photoelectrochemical devices for solar-driven nitrogen fixation. [ABSTRACT FROM AUTHOR]

g-C3N4 has been used as a photocatalyst to overcome the issues of environmental crises and energy shortages. Here, red g-C3N4 nanosheets (Eg: ∼ 1.89 eV) were used as seeds for the edge-epitaxial growth of yellow g-C3N4 (Eg: ∼ 2.59 eV) to form type II heterostructures. The heterostructures revealed superior photocatalytic activity for enhanced H2 (3996 μmol g−1 h−1), CO (3.8 μmol g−1 h−1), and CH4 (1.8 μmol g−1 h−1) evolution. [ABSTRACT FROM AUTHOR]

The development of a highly efficient strategy for the activation of the C–H bond in hydrocarbons is one of the most challenging tasks facing the chemical industries. The synthesis of novel catalysts with atomically dispersed active centers is highly desirable to achieve the maximized atom efficiency. Here we report the controllable preparation of a Co-based single-atom catalyst anchored on a graphitic carbon nitride support (SACo@g-C3N4) with 3.17 wt% Co content, which is successfully applied for the selective oxidation of ethylbenzene (EB) to derive acetophenone (AcPO) via the activated peroxymonosulfate (PMS) oxidant. The Co atoms are chemically bonded with the N atoms of g-C3N4 and present exceptional stability and reusability to resist the applied acidic-oxidative environment. Both the EB conversion and AcPO selectivity were over 95% in this highly selective SACo@g-C3N4/PMS system under mild reaction conditions. The selective conversion of EB into AcPO is attributed to the oxidative radicals generated from the decomposition of PMS molecules via the electron transfer between Co atoms and PMS. Sulfate radicals (SO4˙−) make a greater contribution than others to activate the C–H bond in EB oxidation. This work uncovers a facile and scalable approach for the synthesis of a robust Co-based single atom catalyst (SAC) on a g-C3N4 support and unveils its potential in the oxidation of hydrocarbons via a highly efficient and environmentally benign PMS activation. [ABSTRACT FROM AUTHOR]

Selenide with a narrow band gap can be used as a promising photoelectrode in photoelectrochemical (PEC) water splitting. However, the applications of selenides in high-performance PEC devices are greatly hindered via inducing oxygen into the lattice and generating high-density defects, which result in their environmental instability and high recombination of charge carriers. Here, we have used an in situ selenization strategy to repair the defects of a tin selenide (SnSe) film. The repaired SnSe film under an optimal selenization time shows a remarkable increase in both the limiting photocurrent density and environmental stability by over 3 times in comparison with the pristine film. On the basis of the analysis of the composition and structure, Se element filling in the defects during selenization is critical for suppressing the recombination of charge carriers and reducing the possibility of oxygen bonding to Sn in the bulk of the film. Such strategy can greatly provide a fundamental and technological support in the development of selenide-based devices and enrich the knowledge of defect chemistry for PEC applications. [ABSTRACT FROM AUTHOR]

Nanostructure is the most important aspect in the development of high performance supercapacitors. In this work, we designed and developed new one-dimensional hierarchical hollow nickel–cobalt layered double hydroxide nanocages assembled on MnO2 nanotubes with uniformly dispersed CoS2 nanoparticles, MnO2@NiCo-LDH/CoS2, using a zeolitic imidazolate skeleton (ZIF-67) as the template via multiple hydrothermal and sulfuration processes. This unique one-dimensional hierarchical nanostructure is characterized by a high specific area and high structural stability. The presence of CoS2 nanoparticles in the nanocage increases the electrical conductivity and enhances the stability of the structure. Electrochemical studies show that MnO2@NiCo-LDH/CoS2 electrode materials have a high specific capacitance of 1547 F g−1 at a current density of 1 A g−1 and 1189 F g−1 at 10 A g−1, exhibiting high rate performance (76.9%) and high stability (82.3%), which is substantially better than the performance of most recently reported similar systems. The asymmetric supercapacitor assembled with MnO2@NiCo-LDH/CoS2 and activated carbon has a maximum energy density of 50 W h kg−1 and a maximum power density of 9658 W kg−1. The unique nanostructure and excellent performance of the asymmetric supercapacitor in the present study demonstrate a new platform for developing highly efficient supercapacitor materials with high energy density and high power density. [ABSTRACT FROM AUTHOR]

La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) solid oxide fuel cell cathodes were poisoned by Cr at different temperatures and polarization conditions with a Cr–Fe alloy as the interconnect. Cr induced degradation was analysed by electrochemical impedance spectroscopy (EIS) focusing on the electrochemical resistance (Rchem) that reflects the cathode electrochemical properties. It was found that Rchem increased more with increasing temperatures. However cathodic polarization exhibited a synergistic effect with the temperature, which accelerated the LSCF cathode degradation at 800 °C while lowering the degree of degradation at 900 °C. By correlating complementary micro- and nano-scale microstructure characterization with the impedance analysis, the degradation mechanisms were investigated. A new Cr incorporation mechanism involving preferential formation of nanometre size Fe–Co–Cr–O spinel particles within the cathode up to the cathode/electrolyte interface was found to be responsible for the reduced degradation at 900 °C combined with cathodic polarization. The new mechanism reveals that the activity of B site elements in LSCF and possibly other perovskite cathodes plays an important role under certain combined temperature and polarization conditions, therefore future research in designing Cr resistant perovskite cathode materials may consider strategies that utilize the exsolution of B site elements for the formation of beneficial spinel phases. [ABSTRACT FROM AUTHOR]

g-C3N4 crystalline/amorphous lateral-like homostructures were prepared using crystalline g-C3N4 nanosheets as seeds via sequential edge-epitaxy growth. The homojunction effectively separates photogenerated carriers, resulting in high photo- and electro-catalytic activities. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles (Pd NPs) supported on Ni single atoms encapsulated in carbon nanotubes (NiSA) show a significantly enhanced electrocatalytic activity for the oxidation reactions of methanol, ethanol and glycerol in alkaline media due to an unusual electron withdrawal effect of NiSA on Pd NPs. [ABSTRACT FROM AUTHOR]

The high reactivity between bismuth oxide and cobaltite oxygen electrodes is a bottleneck in developing active and reliable bismuth oxide–cobaltite composite oxygen electrodes for solid oxide cells (SOCs). Herein, a Sr-free Sm0.95Co0.95Pd0.05O3−δ (SmCPd) oxygen electrode decorated with nanoscale Er0.4Bi1.6O3 (ESB) is synthesized and assembled on a barrier-layer-free Y2O3–ZrO2 (YSZ) electrolyte film. The cell with the ESB decorated SmCPd composite oxygen electrode exhibits a peak power density of 1.81 W cm−2 at 750 °C and 0.58 W cm−2 at 650 °C. More importantly, excellent operating stability is achieved in the fuel cell mode at 600 °C for 500 h, and in electrolysis and reversible modes at 750 °C for over 200 h. The results demonstrate the feasibility of applying bismuth oxide–cobaltite composite oxygen electrodes in developing high-performance and durable SOCs. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have been applied as catalysts in the VO2+/VO2+ redox, whereas the mechanism of CNTs for the redox reaction is still unclear. In this work, the mechanism of the VO2+/VO2+ redox is investigated by comparing the electrocatalytic performance of CNTs with different distributions. For different CNTs, the peak current density of the VO2+/VO2+ redox increases with increasing content of oxygen-functional groups on the surface of CNTs, especially the carboxyl group which is proved as active sites for the redox reaction. Moreover, the reversibility of the VO2+/VO2+ redox decreases with increasing defects of CNTs, as the defects affect the charge transfer of the catalytic reaction. Nevertheless, when a multi-walled CNT sample is oxidized to achieve a high content of oxygen functional groups and defects, the peak current density of the redox reaction increases from 38.5 mA mg−1 to 45.4 mA mg−1 whilst the peak potential separation (ΔEp) also increases from 0.176 V to 0.209 V. Overall, a balance between the oxygen functional groups and the defects of CNTs affects the peak current and the reversibility for the VO2+/VO2+ redox. [ABSTRACT FROM AUTHOR]

Metal-oxide nanoclusters (NCs) such as FeOx, CoOx, and NiOx are incorporated into iron phthalocyanine (FePc) supported on graphene, MOx/FePc, via a facile self-assembly method. MOx/FePc electrocatalysts show high activity, selectivity and stability for the electrochemical CO2 reduction reaction (CO2RR) as compared with the corresponding metal phthalocyanines, i.e., FePc, CoPc and NiPc, under identical test conditions. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy reveals that MOx/FePc undergoes a metal ion replacement of the iron center of Pc, forming electrochemically substituted metal Pc, e-MPc where M = Co and Ni, co-existing with the replaced FeOx nanoparticles (NPs) in the vicinity of the e-MPc. The results indicate that the e-MPc with in situ dispersed FeOx NPs, FeOx/e-CoPc and FeOx/e-NiPc exhibits excellent activity, high selectivity and stability for the CO2RR. [ABSTRACT FROM AUTHOR]

Bismuth based oxides have excellent ionic conductivity and fast oxygen surface kinetics and show promising potential as highly active electrode materials in solid oxide cells (SOCs) such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). However, the low melting temperature and high activity of bismuth based oxides severely limit their wide applications in SOCs. Herein, we successfully synthesized a 40 wt% Er0.4Bi1.6O3 decorated La0.76Sr0.19MnO3+δ (ESB–LSM) electrode via a new gelation method and directly assembled it on a Ni–yttria-stabilized zirconia (Ni–YSZ) cermet supported YSZ electrolyte cell without the conventional high temperature pre-sintering step. ESB decoration substantially enhances the electrocatalytic activity of the LSM electrode for the oxygen reduction/evolution reactions (ORR/OER). A YSZ electrolyte cell with the directly assembled ESB–LSM electrode exhibits a peak power density of 1.62 W cm−2 at 750 °C, significantly higher than 0.48 and 0.88 W cm−2 obtained on cells with a directly assembled pristine LSM and LSM–YSZ composite electrode, respectively. Most importantly the cells with the directly assembled ESB–LSM oxygen electrodes show excellent stability in SOFC, SOEC and reversible SOC operating modes for over 200 h. The present study demonstrates a significant advancement in the development of bismuth based oxide decorated high performance and stable oxygen electrodes for reversible SOCs. [ABSTRACT FROM AUTHOR]

A metal–organic framework (MOF) seed-mediated deposition route is developed to synthesize MOF/graphene oxide (GO)/MOF nano-sandwiches with core–shell structured MOF (i.e. ZIF-8@ZIF-67) crystals uniformly distributed on GO. Due to the well controllable growth rate, ZIF-8 seeds are first deposited on GO. Then, ZIF-67 species are selectively deposited on the surface of ZIF-8 to form core–shell structures owing to their similar crystal structure and unit cell parameter. Compared with the direct deposition of ZIF-67 crystals on GO, this MOF seed-mediated synthesis can effectively prevent the over-growth and inhomogeneous distribution of ZIF-67 crystals. The GO/core–shell MOF composites are further demonstrated to be an excellent precursor for cobalt/N-doped carbon nanosheets, which are efficient nonprecious metal catalysts for oxygen reduction reactions, and exhibit a high onset potential (∼0.93 V versus reversible hydrogen electrode, vs. the RHE) and large kinetic current density (∼101 mA mg−1 at 0.80 V vs. the RHE). Such novel carbon materials derived from the core–shell structured MOF also show better catalytic performance than those derived from both GO/ZIF-8 and GO/ZIF-67 prepared under the same conditions. This work offers an alternative strategy to develop MOF-derived carbon-based composites using GO/core–shell structured MOFs as a kind of fresh precursors. [ABSTRACT FROM AUTHOR]

Cobaltite-based double perovskite oxides with high electrocatalytic activity and conductivity have been developed as high-performance cathode alternatives for solid oxide fuel cells (SOFCs). However, the use of cobaltite-based double perovskites on Y2O3 stabilized ZrO2 (YSZ)-based SOFCs requires the application of a doped ceria barrier layer. This is due to their poor chemical and physical compatibility with the YSZ electrolyte during high-temperature sintering and fabrication processes. Here we report a viable approach to in operando assemble double perovskites such as PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), on YSZ electrolyte and thus effectively form an electrode/electrolyte interface without high-temperature processing. The electrochemical performance of the in situ assembled PBSCF cathode is comparable to that of the cathode prepared by conventional methods. A single cell with an in situ assembled PBSCF–GDC (Gd-doped ceria) cathode achieved a peak power density (PPD) of 1.37 W cm−2 at 750 °C and exhibited a high stability at 500 mA cm−2 and 750 °C for 100 h. Surface and cross-sectional microstructure analysis offer solid evidence that the PBSCF–GDC cathode/YSZ electrolyte interface was formed by electrochemical polarization. This work offers new opportunities to effectively and effortlessly use high-performance double perovskite cathodes in commercial SOFCs. [ABSTRACT FROM AUTHOR]

In this communication, cobaltite-based perovskite (CBP) cathodes are directly applied on the yttria-stabilized zirconia (YSZ) electrolyte via an in situ assembly process without the addition of a doped ceria interlayer and pre-sintering at high temperatures. The results demonstrate for the first time that a CBP electrode/YSZ electrolyte interface can be formed in situ under cathodic polarization at a solid oxide fuel cell (SOFC) operating temperature of 750 °C. Nevertheless, the performance of cells with Sr-containing CBP cathodes deteriorates due to the surface segregation of Sr species and formation of a Sr-rich reaction layer at the interface. However, the stability and power density of cells with in situ assembled CBP cathodes can be further enhanced by B-site doping or by using a Sr-free CBP. The direct application of CBPs on the YSZ electrolyte revolutionizes the design of intermediate temperature SOFCs. [ABSTRACT FROM AUTHOR]

A novel three-dimensional, interconnected conducting layer network, comprised of crumpled nitrogen- and boron-dual-self-doped graphene sheets (NBGs) with an ultrahigh content of 7.72 at% nitrogen and 7.18 at% boron, has been synthesized through one-step thermolysis, using a borane-tert-butylamine complex as a precursor. The unique self-assembled 3D network structure offers shortened tunnels for lithium ion and electron transport and conduces the adsorption/desorption of lithium ions. As an anode material, NBGs-1000 reveals a high reversible capacity of up to 909 mA h g−1 and an excellent discharge capacity of 877 mA h g−1 after 125 cycles. It also exhibits a remarkable rate performance, including large capacities of 429 mA h g−1 and 318 mA h g−1 at 1 A g−1 and 2 A g−1, respectively. In contrast, a commercial graphite electrode has a capacity of less than 50 mA h g−1 at 1 A g−1. This demonstrates that crumpled NBGs are an extraordinary active anode material exhibiting a high capacity and good stability for lithium ion batteries, owing to their large surface area, heteroatomic defects, and the unique crumpled structure. [ABSTRACT FROM AUTHOR]

It is highly desirable but challenging to develop a highly active as well as durable bifunctional electrocatalyst for the reversible oxygen reduction reaction and evolution reaction (ORR & OER). Here a new class of bifunctional oxygen electrocatalysts has been developed based on ultrafine transition metal-oxide nanoparticles (NPs), such as NiO, FeO or NiFeO, embedded in an amorphous MnOx shell, where the embedded NP core contributes to the high OER activity and the porous amorphous MnOx shell functions as an effective ORR catalyst as well as providing effective structural confinement to the metal-oxide NP core. The best performance was obtained for NiFeO@MnOx, exhibiting a potential gap, ΔE, of 0.798 V to achieve a current of 3 mA cm−2 for the ORR and 5 mA cm−2 for the OER in 0.1 M KOH solution, better than that of Ir/C (0.924 V) and Pt/C (1.031 V). Most importantly, NiFeO@MnOx shows superior stability due to the outstanding structural confinement effect of the amorphous MnOx, achieving a ΔE of 0.881 V after 300 cycles, outperforming 1.093 V obtained for the state-of-the-art Ir–Pt/C oxygen electrocatalysts. [ABSTRACT FROM AUTHOR]

The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200 °C. [ABSTRACT FROM AUTHOR]

Dye sensitized water splitting photoelectrochemical (PEC) cells generally require the attachment of photosensitizer to a semiconductor and a water oxidation catalyst (WOC). Here we report for the first time that dye, including zinc phthalocyanine (ZnPc), cobalt phthalocyanine (CoPc) and tris(bipyridine)ruthenium(ii) (Rubpy), sensitized or functionalized pristine carbon nanotubes (dye/CNTs) without the presence of semiconducting oxides and conventional WOCs have unusually high activity for PEC water splitting in alkaline solutions under ultraviolet (UV) and visible light. The PEC activities of dye/CNTs show distinctive volcano curves as a function of number of walls with the highest activity observed on double- and triple-walled CNTs (DWNTs and TWNTs). For example, the photocurrent of the ZnPc functionalized TWNTs at 1.2 V vs. RHE is 0.32 mA cm−2, which is ∼4 times of 0.09 mA cm−2 obtained on the ZnPc functionalized single-walled CNTs (SWNTs) and one order of magnitude higher than 0.02 mA cm−2 on ZnPc functionalized multi-walled CNTs (MWNTs). On the other hand, the photocurrents are negligible on pristine CNTs, less than 0.005 mA cm−2 under identical experimental conditions. This remarkable feature is due to the unique charge separation ability of the dye/CNTs, where the photoexcited electrons are transferred to the inner tubes via the electron tunneling under the dc bias voltage, and the significant electrocatalytic activities of DWNTs and TWNTs for the water oxidation reaction. The results provide new opportunities for the development of artificial photosynthetic systems via the manipulation of the quantum properties of CNTs. [ABSTRACT FROM AUTHOR]

High temperature solid oxide cells (SOCs) are attractive for storage and regeneration of renewable energy by operating reversibly in solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes. However, the stability of SOCs, particularly the deterioration of the performance of oxygen electrodes in the SOEC operation mode, is the most critical issue in the development of high performance and durable SOCs. In this study, we investigate in detail the electrochemical activity and stability of La0.8Sr0.2MnO3 (LSM) oxygen electrodes in cyclic SOEC and SOFC modes. The results show that the deterioration of LSM oxygen electrodes caused by anodic polarization can be partially or completely recovered by subsequent cathodic polarization. Using in situ assembled LSM electrodes without pre-sintering, we demonstrate that the deteriorated LSM/YSZ interface can be repaired and regenerated by operating the cells under cathodic polarization conditions. This study for the first time establishes the foundation for the development of truly reversible and stable SOCs for hydrogen fuel production and electricity generation in cyclic SOEC and SOFC operation modes. [ABSTRACT FROM AUTHOR]

Conventional Ni-based cermet anodes such as Ni-gadolinia doped ceria (Ni-GDC) suffer from low carbon deposition resistance in direct methane solid oxide fuel cells (SOFCs). Here we show that impregnating proton conducting perovskites like BaCe0.9Y0.1O3−δ (BCY) and BaCe0.9Yb0.1O3−δ (BCYb) in Ni-GDC not only improves the initial polarization performance but also, most importantly, significantly enhances the stability in wet methane fuel (3% H2O in CH4) by inhibiting carbon deposition and formation. In wet methane, the voltage of the cell with the conventional Ni-GDC anode decreases rapidly from 0.58 to 0.15 V within 6 h at 200 mA cm−2 and 750 °C. In contrast, in the case of the cells with BCY + Ni-GDC and BCYb + Ni-GDC anodes, the cell voltage is essentially constant at 0.62–0.65 V over a period of 48 h tested under identical conditions. The microstructure and Raman spectroscopy analysis reveal that the impregnated fine BCY and BCYb particles are preferentially distributed on the surface of the Ni grains in the Ni-GDC anode, decreasing the exposed surface of Ni grains and inhibiting carbon deposition. Also, the proton conducting and fine BCY and BCYb particles can adsorb and decompose water, which in turn reacts with deposited carbon to form CO and H2, alleviating the carbon deposition problem in the anode and thus significantly improving the cell stability of direct methane SOFCs. [ABSTRACT FROM AUTHOR]

An oxygen electrode finds many applications in various electrochemical energy conversion devices such as fuel cells and metal–air batteries. Highly efficient gas–proton transportation at the electrode is very important to enhance the power density of these devices. Herein, we report the construction of a highly efficient oxygen electrode with substantially improved proton conductivity and gas transportation properties using three dimensionally ordered macroporous Nafion/Cs2.5H0.5PW12O40, 3DOM Nafion/CsHPW, scaffold supported Pt/C nanocomposites. The best results were obtained for cells with 3DOM Nafion/CsHPW with 10% CsHPW, achieving a maximum power density of 955 mW cm−2, 31% higher than 730 mW cm−2 for the cell with the conventional Nafion-binder based oxygen electrode. The proton conductivity of the 10% 3DOM Nafion/CsHPW catalyst layer is 1.56 × 10−2 S cm−1, 112% higher than 7.35 × 10−3 S cm−1 measured for the conventional catalyst layer with the Nafion binder. The results demonstrate the significant advantages of the oxygen electrodes with the Pt/C-3DOM Nafion/CsHPW architecture over the conventional Nafion-binder based ones, with the significantly enhanced proton conductivity of uniformly distributed CsHPW nanoparticles (NPs) and much better gas diffusion properties of the 3DOM architecture. [ABSTRACT FROM AUTHOR]

A BaO infiltrated La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) cathode shows remarkable tolerance and resistance towards chromium via the formation of BaCrO4 instead of SrCrO4 on the electrode surface, preventing the excess Sr deficiency at the A-site of LSCF perovskite and thus mitigating the Cr poisoning effect. [ABSTRACT FROM AUTHOR]

Hierarchical mesoporous yolk–shell structured carbon nanospheres (YSCNs) with an ordered mesoporous carbon core and a microporous carbon shell show excellent electrochemical performance with a maximal specific capacitance of 159 F g−1. [ABSTRACT FROM AUTHOR]

For the first time it has been demonstrated that number of walls in pristine carbon nanotube (CNT) supports has significant effects on the electrocatalytic activity of Pt nanoparticles (NPs) towards methanol and formic acid oxidation reactions in alkaline solution, showing a distinctive volcano-type dependence of the catalytic performance on the number of walls of CNTs. In this study, Pt NPs of a similar size were uniformly self-assembled on CNTs with different numbers of walls and outer diameters to be used as model catalysts. The electrocatalytic activity and stability of Pt NPs showed distinctive volcano-type curves as a function of the number of walls with the best results being obtained using CNTs with an average of 7 walls. Such an unusual promotion effect can be ascribed predominantly to the high affinity of oxygen-containing species such as OHads, which facilitate the removal of adsorbed CO species and promote fast electron transfer between the outer walls and the inner tubes of CNTs, most likely through electron tunneling under the electrochemical polarization driving force. This study demonstrates the new possibility of tailoring the electrocatalytic properties of precious metal catalysts via altering the electronic and quantum transport properties of their CNT supports. [ABSTRACT FROM AUTHOR]

A novel high-temperature proton exchange membrane (PEM) consisting of polyvinylpyrrolidone (PVP) and polyvinylidene fluoride (PVDF) has been successfully prepared by a simple and scalable polymer blending method. PVP is miscible with PVDF, forming a single-phased PVDF-PVP polymer with excellent flowability and uniform microstructure when the PVP content is equal to or higher than 40 wt% due to the effective hydrogen bonding between the functional groups of PVP and PVDF. A proton conductivity of 0.093 S cm-1 was obtained for a 20 wt% PVDF-80 wt% PVP membrane with a H3PO4 doping level of 2.7 at 200 °C under anhydrous conditions, compatible with the state-of-the-art PBI/PA membranes. PEM fuel cells with PA/PVDF-PVP membranes showed a high power density of 530 mW cm-2 at 180 °C in H2/O2 and excellent stability without external humidification. The results indicate the high structural and chemical stability and high retention capability of the blended membranes for doped PA at elevated operation temperatures. The PVDF-PVP hybrids show promising potential as alternative PEMs for fuel cells at elevated high temperatures and under anhydrous conditions. [ABSTRACT FROM AUTHOR]

The co-doped lanthanum silicate oxyapatites, La9.5A0.5Si5.5Fe0.5O26.5 (A = Ba, Sr, and Ca), are synthesized by the high-temperature solid state reaction process. The phase formation and structure properties of undoped lanthanum silicate oxyapatite (La9.67Si6O26.5, LSO), Fe-doped lanthanum silicate oxyapatite (La10Si5FeO26.5, LSFO) and co-doped lanthanum silicate oxyapatites (La9.5A0.5Si5.5Fe0.5O26.5, A = Ba, Sr, and Ca) are characterized by X-ray diffraction (XRD) and scanning electron spectroscopy (SEM). The effect of co-doping of A (A = Ba, Sr, Ca) and Fe on the microstructure, sinterability and oxide ion conductivity of lanthanum silicate oxyapatites is investigated in detail. The results show that, as compared to LSO and LSFO oxyapatites, co-doping of A (A = Ba, Sr, and Ca) and Fe significantly benefits the sintering and densification process, and enhances the oxide ion conductivity. For co-doped oxyapatites, the oxide ion conductivities are related to the dopant size, the best properties are obtained for the oxyapatite co-doped with Ca and Fe. The co-doped La9.5Ca0.5Si5.5Fe0.5O26.5 (LCSFO) oxyapatite is a good electrolyte for SOFCs, with an oxide ion conductivity of 1.39 × 10−2 S cm−1 at 800 °C and a low activation energy of 90.71 kJ mol−1. The bulk density and oxide ion conductivities of co-doped oxyapatite ceramics increase significantly with the increase of the sintering temperature. The grain bulk and grain boundary resistances of La9.5Ba0.5Si5.5Fe0.5O26.5 (LBSFO), La9.5Sr0.5Si5.5Fe0.5O26.5 (LSSFO) and LCSFO oxyapatite ceramics are significantly smaller than those of LSO and LSFO oxyapatite ceramics sintered under the identical conditions. [ABSTRACT FROM AUTHOR]

A comprehensive strategy has been developed to synthesize highly ordered mesoporous Nafion membranes with different structure symmetries including 2D hexagonal (2D-H), 3D face-centered (3D-FC), 3D cubic-bicontinuous (3D-CB) and 3D body-centered (3D-BC), using a soft template method with the assistance of a silica colloidal mediator. The Nafion membrane derived from the self-assembled mesoporous Nafion–silica composites maintained the microstructures of the silica framework, which was confirmed by small angle X-ray scattering (SAXS) and TEM. The in situ time-resolved synchrotron SAXS clearly indicates that the presence of silica colloids is critical for the formation of the highly ordered mesoporous structured phase in the precursor solution. The best results are observed on Nafion membranes with 2D-H structure in terms of proton conductivity and cell performance under reduced relative humidity (RH) conditions, achieving proton conductivities of 0.08, 0.062 and 0.038 S cm−1 at 100, 40 and 0%RH, respectively. Moreover, the power output of the mesoporous Nafion membrane cells show a S-shaped dependence on RH and are stable under anhydrous conditions (i.e., 0% RH), demonstrating the outstanding high water retention capability of the mesoporous structure of the membranes. [ABSTRACT FROM AUTHOR]

Borosilicate-based glasses are the most common sealant materials for solid oxide fuel cells (SOFCs). However, boron species vaporizing from glass sealants poison and degrade the electrocatalytic activity of cathodes of SOFCs. In this study, we report the development of a new class of glass sealants based on bismuth and zinc doped borosilicates with significantly suppressed boron volatility. Doping Bi induces the [BO3] → [BO4] transition with an increased binding energy of boron, while addition of Zn leads to the formation of a boron-containing compound, Sr3B2SiO8, with significantly increased stability of boron in the glass matrix. Using La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) perovskite oxide as the cathode to assess the boron deposition and poisoning, the results indicate that the polarization performance of the LSCF cathode for the O2 reduction reaction in the presence of Bi and Zn doped glass is very stable with a negligible change in the microstructure of the electrodes. In contrast, in the case of conventional borosilicate glass, boron preferentially deposits in the electrode/electrolyte region under cathodic polarization, forming primarily LaBO3, disintegrating the perovskite structure and significantly degrading the electrochemical activity of the LSCF cathodes. Doping Bi or Zn remarkably reduces the boron volatility of the glass, thus effectively inhibiting the poisoning of boron species on the microstructure and electrocatalytic activity of SOFC cathodes such as LSCF. The present results demonstrate for the first time that the Bi and Zn doping is the most effective strategy to minimize the boron poisoning from the source by suppressing the boron vaporization of borosilicate-based glass sealant materials. [ABSTRACT FROM AUTHOR]

A novel active graphene-like nanosheet (AGN) with a high specific surface area is first developed as an efficient electrocatalyst support synthesized through an efficient ion-exchange-assisted synthesis route. The AGN shows high electronic conductivity and strong cohesive force and distribution effects toward the catalyst nanoparticles. The AGN supported PdxPty bimetallic catalyst system with ultralow Pt loading exhibits excellent catalytic performance and superb durability for the oxygen reduction reaction of fuel cells, giving a high mass activity of 1930 mA mgPt-1 at 0.9 V vs. RHE. [ABSTRACT FROM AUTHOR]