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Electrochemical reduction of nitrate into ammonia (NO 3 -RR) has attracted great attentions because of the potential application for environmental remediation and energy storage. Despite many pioneering works on electrocatalysts development, the correlation between material properties and NO 3 -RR activity is still not fully understood. Herein, taking layered Ruddlesden-Popper type oxide La 2 CuO 4 as a model system, we demonstrate B-site cation doping as an effective approach for modulating NO 3 -RR activities. While Co dopant at Cu site strongly enhanced the NO 3 -RR activity and NH 3 selectivity, Zn and Ni dopants lead to slightly enhanced and suppressed NO 3 -RR performance, respectively. The distinct reaction kinetics of NO 3 -RR on La 2 Cu 0.8 M 0.2 O 4 with different dopants are further revealed by in-situ Fourier transform infrared spectroscopy measurement. Synchrotron-based X-ray absorption spectroscopy showed that B-site doping can effectively regulate metal-oxygen hybridization, leading to strongly tuned surface adsorption characteristics and NO 3 -RR activity. The results of this work can guide the design of highly active (electro)catalysts for environmental and energy devices. [Display omitted] • B-site doping modulated the metal-oxygen hybridization of La 2 CuO 4. • Established the correlation between metal-oxygen hybridization and NO 3 -RR activity. • La 2 Cu 0.8 Co 0.2 O 4 exhibited highest NO 3 -RR activity and NH 3 selectivity. • Competing HER on La 2 Cu 0.8 Ni 0.2 O 4 suppressed the NO 3 -RR performance. [ABSTRACT FROM AUTHOR]

The durability and electro-catalytic activity for oxygen reduction reaction (ORR) of solid oxide fuel cells (SOFCs) cathode often suffer from severe degradation due to poisoning effects such as Cr from interconnectors. Here we report our findings in the development of a Cr-tolerant catalyst, BaCoO 3-x (BCO) nano-particles, which can dramatically enhance the ORR activity and durability of a state-of-the-art La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-x (LSCF) cathode exposed to Crofer 22APU. For example, the polarization resistance (R p) of a bare LSCF cathode increases from ~0.4 to ~1.5 Ωcm2 after 100 hs exposure to Cr in air with 3% H 2 O at 750 °C. In contrast, R p of a BCO-coated LSCF cathode remains to be ~0.05 Ωcm2 under the same condition, suggesting that BCO is catalytically active to ORR but inert to Cr-poisoning. At 700 °C, the single cells with the BCO-coated LSCF cathode show an excellent peak power density of ~0.514 Wcm−2 and significantly enhanced durability (degradation rate of 0.086 %h−1 at 0.8 V), much better than those of cells with a bare LSCF cathode (~0.448 Wcm−2 and degradation rate of 0.31 %h−1 at 0.8 V). Raman analysis indicated that the presence of the BCO catalyst coating greatly reduced the amount of Cr accumulated on the cathode surface, thus alleviating the formation of SrCrO 4. Image 1 • Surface coating of barium cobaltite is coated on LSCF surface. • The coating is active to oxygen reduction but inert to chromium poisoning. • The coating enhanced the Cr-tolerance of LSCF under accelerated testing conditions. • Raman analysis indicated that surface coating can reduce the formation of SrCrO 4. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts for oxygen evolution reaction (OER) is of significant importance for the application of many energy conversion and storage technologies. Perovskite oxides have attracted great attention as potential OER electro-catalysts. Their performance, however, are strongly limited by large particle size, owing to the high synthesis temperature. Herein, we report a facile top-down strategy for fabricating perovskite oxide nanostructures with large surface area and strongly improved intrinsic OER activity. SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ (SNCF) particles with micro size are treated by (NH 4) 2 Fe(SO 4) 2 saturated solution for different time length at room temperature. The obtained catalysts exhibit significantly increased surface area with nanosheet structure in the outer layer. Furthermore, cobalt on the surface are reduced from Co3+ to Co2+, suggesting oxygen vacancy formation on the surface. The defective SNCF nanostructure exhibits significantly improved OER activity and good stability. The facile methodology reported in this work can be generally applied to other oxide electrocatalysts for energy applications. Image 1 • A top-down strategy was developed for fabricating perovskite oxide nanostructure. • Perovskite oxide SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ (SNCF) was treated by (NH 4) 2 Fe(SO 4) 2 solution. • The obtained SNCF nanostructure was with abundant surface oxygen vacancies. • Solution treatment strongly enhanced the OER activity of SNCF. [ABSTRACT FROM AUTHOR]

Low-cost transition metal oxides (TMO) has received extensive attention as new-generation oxygen evolution reaction (OER) catalysts. In recent years, introducing oxygen defects via various strategies emerged as an efficient way to increase electro-catalytic activity of TMO. Despite many successful examples, the physical and chemical origin of such enhanced OER activity induced by oxygen defects is still not well understood. In this work, we systematically investigate the correlation between the concentration of oxygen vacancies and OER activity by using a NiO thin film model system grown by pulsed laser deposition. Oxygen vacancies are introduced into NiO thin films by Ar plasma treatments with different power (50 W, 100 W, and 150 W). The OER activities of NiO thin films are found to be significantly enhanced after plasma treatment. The improvement in electrochemical OER performance is attributed to the creation of oxygen defects, which lead to the strongly modified surface adsorption properties, as confirmed by X-ray photoelectron spectroscopy and contact angle measurements. Our results demonstrate that plasma treatment as a promising method for precisely tuning physical and chemical properties of TMO through oxygen defects engineering to obtain high performance electro-catalysts. Image 1 • Thin films are used as model systems to reveal the role of oxygen defects. • NiO thin films show strongly enhanced OER activity after Ar plasma treatments. • Oxygen vacancies change the surface adsorption characteristics of NiO thin film. • The NiO thin film treated by 50 W Ar plasma shows the highest OER activity. [ABSTRACT FROM AUTHOR]

High voltage LiNi 0.5 Mn 1.5 O 4 material is a promising cathode for lithium ion battery, but the unsatisfied cycle stability hinders its further development in higher energy density battery. Amorphous terpolymer poly(butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)), which possesses good affinity with carbonated liquid electrolyte and high adhesion ability, is used together with traditional poly(vinylidene fluoride) (PVDF) binder to improve the cyclic performance of LiNi 0.5 Mn 1.5 O 4 cathode. The retention ability of discharge capacity is 92% for Li/LiNi 0.5 Mn 1.5 O 4 coin cell after 300 cycles at 1 C rate when the cathode uses the co-binders of PVDF and P(BMA-AN-St) (2:1 in weight), compared with 55% capacity retention for the cathode fabricated with PVDF binder alone. From the physical and electrochemical characterizations of the cycled electrode, it is found that the introduced terpolymer enhances the liquid electrolyte uptake ability of LiNi 0.5 Mn 1.5 O 4 cathode and the adhesion strength inside the particles by building a better interconnected conductive structure. Furthermore, the improved cycle stability of co-binder based cathode is contributed to the passivating layer formed by the terpolymer on the surface of LiNi 0.5 Mn 1.5 O 4 particles, which effectively suppresses the decomposition of liquid electrolyte at high voltage and maintains the structural integrity of active material in the repeated intercalation/de-intercalation process. • P(BMA-AN-St) co-binder improves the cyclic stability of LiNi 0.5 Mn 1.5 O 4 cathode. • Electrolyte uptake and adhesive ability of electrode using co-binder are enhanced. • P(BMA-AN-St) forms the passivating layer on the surface of LiNi 0.5 Mn 1.5 O 4 particles. • The polymer layer effectively suppresses the decomposition of liquid electrolyte. • The polymer layer also protects the structural integrity of cathode material. [ABSTRACT FROM AUTHOR]

In this paper, we design a novel gel polymer electrolyte (GPE), based on polyethylene (PE) supported poly(butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)) terpolymer reinforced by doping 10 wt.% nano-SiO 2 , to be possible application in high voltage lithium ion battery. The physical characterization indicates that P(BMA-AN-St)/SiO 2 /PE membrane has multi-layered and cross-linked network structure with the pore diameter of about 1 μm, leading to the highest electrolyte uptake ability of 257% compared with the value of 118% for PE support. Electrochemical performance exhibits that the corresponding GPE presents highest ionic conductivity of 1.9 × 10 −3 S cm −1 at room temperature and the improved oxidative stability from 4.2 V (PE support saturated with liquid electrolyte) to 5.2 V (vs. Li/Li + ). Thus, the high voltage cathode LiNi 0.5 Mn 1.5 O 4 using nano-SiO 2 doped GPE presents excellent cyclic stability and rate performance, which retains 93.0% of its initial discharge capacity after 150 cycles at 0.2 C rate and keeps 95.0% discharge capacity at 2 C rate of that at 0.1 C rate, while PE support saturated with liquid electrolyte has 87.9% capacity retention after 150 cycles and with the rate capacity value of 86.8% at the same rate test condition. [ABSTRACT FROM AUTHOR]