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A template‐free, one‐step synthesis of nano‐IrO2 on a layered Mn−Co birnessite support was developed to induce the catalyst‐support interaction. The IrO2 nanoparticles were prepared with inherent crystal lattice strain, which is derived from the Ir‐O−Mn mismatch at the interface. The oxidation state of iridium is higher than IrIV, revealing the electron transfer to the substrate. On account of the crystal lattice distortion and electronic manipulations being favorable to the oxygen evolution reaction (OER), the as‐synthesized composite exhibited excellent OER activity and stability. The improved catalytic nature was followed by enhancement in the electrochemical active surface area, mass specific activity, and intrinsic activity. Moreover, the Tafel slope of 42 mV dec−1 reveals better reaction kinetics for IrO2/Mn−Co (2 : 1)‐birnessite than many previously reported catalysts despite the low precious noble metal content in the as‐synthesized composite. Conclusively, we have proven that the strain engineering holds vital importance in forming catalyst‐support interaction and rational design of catalysts. [ABSTRACT FROM AUTHOR]

Alloying Pt with 3d transition metals results in the d-band center moving away from the Fermi level, creating compressive strain. The adsorption strength of the reactants should not be too strong or too weak. The presence of compressive strain, which can increase the orbital overlap between *H and *O, results in the reduction of energy barriers of H-assisted N–O bond activation in terms of the Langmuir–Hinshelwood (L–H) reaction route. Our findings provide guidelines to design more efficient H2-SCR catalysts. [ABSTRACT FROM AUTHOR]

The design of efficient and stable electrocatalysts is still crucial to realize oxygen evolution reaction (OER) in acid and corrosive environment. Inspired by the metal/metal oxides catalysts, we hydrothermally synthesized Ir-IrO2 composites duly confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive spectrometer (EDS), X-ray absorption data, and transmission electron microscope results. A low onset over-potential of merely 234 mV and a Tafel slope of 53 mV dec−1 were obtained for the prepared catalyst Ir-IrO2_0.5AF. In addition, Ir-IrO2_0.5AF catalyst retained high activity for long time under constant potential polarization. The enhanced performance is attributed to the introduction of lower valence Ir as hydrogen acceptor: hydrogen transfers from -OOH intermediate in OER to adjacent H acceptor site, forming intermediate with relatively lower Gibbs free energy, and resulting in higher activity. The present study emphasizes on important role of the lower valence composition in launching H acceptors and providing wide opportunities toward rational designing of efficient and stable electro-catalysts. [ABSTRACT FROM AUTHOR]

Here, we report an effective strategy to lower Ir consumption and boost the OER performance in acid by loading IrO2 onto MnO2, in which the IrO2 crystals are well dispersed and undergo a so-called z-extension Jahn–Teller distortion in the octahedral structure. Compared with IrO2, the mass activity and intrinsic activity for IrO2/MnO2 were largely increased. [ABSTRACT FROM AUTHOR]

The lattice strain of IrO2 plays a critical role in determining its OER activity. The Ir–O bond length change in IrO6 coordination induces lattice strain. Increasing the annealing temperature results in a stretching strain along the c axis and a compressive strain on the a and b axes, leading to a larger c/a ratio. Enhancing the lattice strain decreases the c/a ratio, which is beneficial for improving OER activity. [ABSTRACT FROM AUTHOR]

The anodic reaction of oxygen evolution reaction (OER), an important point for electrolysis, however, remains the obstacle due to its complicated reaction at electrochemical interfaces. Iridium oxide (IrO2) is the only currently known 5d transition metal oxide possessing admirable OER activity. Tremendous efforts have been carried out to enhance the activity of iridium oxides. Unfortunately there lies a gap in understanding what factors responsible for the activity in doped IrO2 or the novel crystal structure. Based on two metallic pyrochlores (Bi2Ir2O7 and Pb2Ir2O6.5) and IrO2. It has been found that there exists a strong correlation between the specific OER activity and IrO6 coordination geometry. The more distortion in IrO6 geometry ascends the activity of Ir sites, and generates activity order of Pb-Ir > IrO2 > Bi-Ir. Our characterizations reveal that distorted IrO6 in Pb-Ir induces a disappearance of J = 1/2 subbands in valence band, while Bi-Ir and IrO2 resist this nature probe. The performed DFT calculations indicated the distortion in IrO6 geometry can optimize binding strength between Ir-5d and O-2p due to broader d band width. Based on this insight, enhancement in OER activity is obtained by effects that change IrO6 octahedral geometry through doping or utilizing structural manipulation with nature of distorted octahedral coordination. [ABSTRACT FROM AUTHOR]

Herein, an enhanced green production of xanthan gum has been achieved by utilizing orange peels. Response surface methodology and kinetic modeling were adapted for the process optimization and its influence on scale up production respectively. Optimal conditions for the maximum xanthan production were 1.62% acid hydrolysis, 85% carbon source of orange peel hydrolysate and 30.4 °C temperature. Furthermore, the optimized treatment was conducted in the batch culture fermentor to observe the associated variations during scale up process. In bio-fermentor, to the first time ever, xanthan production along with reducing sugar conversion and utilization rates reached 30.19 g/L, 69.29% and 99.99%, respectively. Employed characterization techniques of FTIR, XRD and HPLC confirmed the fermented product as xanthan gum and obtained an average molecular weight of 1.01 × 10 6 g/mol. This work on account of optimized process parameters presented maximum xanthan production from a waste material. [ABSTRACT FROM AUTHOR]

Synthesizing oxygen evolution reaction (OER) catalysts with enhanced activity by codoping has been proven to be a feasible approach for the efficient use of noble metals via renewing their basic intrinsic properties. In continuation of the research in codoping, we prepare a ruthenium-based bimetallic doped catalyst Mn x Fe y Ru 1- x - y O 2 with an outstanding OER activity as compared to pure RuO 2 , one of the state-of-the-art OER catalysts. The synthesized codoped RuO 2 with a Mn/Fe molar ratio of 1 reflected a Tafel slope of only 41 mV dec -1 , which is appreciably lower than 64 mV dec -1 for pure RuO 2 . The X-ray photoelectron spectroscopy (XPS) performed reveals that oxygen vacancy and manganese valency are the key factors of the OER activity for codoped catalysts., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Alloying Pt with 3d transition metals results in the d-band center moving away from the Fermi level, creating compressive strain. The adsorption strength of the reactants should not be too strong or too weak. The presence of compressive strain, which can increase the orbital overlap between *H and *O, results in the reduction of energy barriers of H-assisted N-O bond activation in terms of the Langmuir-Hinshelwood (L-H) reaction route. Our findings provide guidelines to design more efficient H2-SCR catalysts.

Here, we report an effective strategy to lower Ir consumption and boost the OER performance in acid by loading IrO2 onto MnO2, in which the IrO2 crystals are well dispersed and undergo a so-called z-extension Jahn-Teller distortion in the octahedral structure. Compared with IrO2, the mass activity and intrinsic activity for IrO2/MnO2 were largely increased.

We systematically characterized the perovskite-like oxides Ca 2 IrO 4 and CaIrO 3 as the oxygen evolution reaction (OER) catalysts. Compared with IrO 2 , universally accepted as the current state-of-the-art OER catalyst, Ca 2 IrO 4 showed an excellent OER catalytic activity in an acidic environment, whereas CaIrO 3 did not. X-ray photoelectron spectroscopy (XPS) spectra showed that the oxidation of iridium in Ca 2 IrO 4 and CaIrO 3 was slightly beyond +4. X-ray absorption near-edge structure (XANES) spectra illustrated that the IrO 6 octahedral geometric structure in Ca 2 IrO 4 and CaIrO 3 showed differences. The IrO 6 octahedral is asymmetrically distorted and uniformly compressed in Ca 2 IrO 4 and CaIrO 3 . Therefore, we propose that the IrO 6 octahedral distortion plays an important role in the OER activities., Competing Interests: The authors declare no competing financial interest.

The lattice strain of IrO 2 plays a critical role in determining its OER activity. The Ir-O bond length change in IrO 6 coordination induces lattice strain. Increasing the annealing temperature results in a stretching strain along the c axis and a compressive strain on the a and b axes, leading to a larger c/a ratio. Enhancing the lattice strain decreases the c/a ratio, which is beneficial for improving OER activity.

Developing more efficient and stable oxygen evolution reaction (OER) catalysts is critical for future energy conversion and storage technologies. We demonstrate that inducing a lattice strain in IrO 2 crystal structure due to interface lattice mismatch enables an enhancement of the OER catalytic activity. The lattice strain is obtained by the direct growth of IrO 2 nanoparticles on a specially exposed surface of α-MnO 2 nanorods via a simple two-step hydrothermal synthesis. Interestingly, the prepared hydride OER activity increases with a lower IrO 2 grown mass, which offers an opportunity to reduce the usage of precious iridium and ultimately obtains a specific mass activity of 3.7 times than that of IrO 2 prepared under the same conditions and exhibits equivalent stability. The lattice mismatch in the underlying interface induces the formation of lattice strain in IrO 2 rather than the charge transfer between the materials. The lattice strain changes are in good agreement with the order of the OER activity. Our experimental results indicate that using the special exposed surface substrates or tuning the supporting morphology structure can manipulate the catalyst materials lattice strain for the design of more efficient OER catalysts.

Nanomaterials have increasingly gained a great amount of interest due to their widespread applications, while their potential impacts on invertebrates in soil lack thorough investigation. This study is mainly aimed at determining the acute and subacute toxicity to the earthworm Eisenia fetida, induced by different levels of nanoscale zerovalent iron (nZVI) (100, 500, 1000 mg kg -1 ) in natural soils. The results showed that compared to the controls, exposure to 500 and 1000 mg kg -1 of nZVI significantly (P < 0.05) inhibited growth and respiration and increased avoidance response in earthworms. The perturbations of antioxidant enzyme activities (superoxide dismutase-SOD and catalase-CAT), malondialdehyde (MDA) content, and reactive oxygen species (ROS) clearly revealed that oxidative stress was induced in E. fetida exposed to nZVI. Good correlations were observed in current results among the growth, respiration, MDA, and ROS (R > 0.8; P < 0.05), and that ROS was the most sensitive parameter in response to the stress caused by nZVI. Additionally, the histopathological examination of transverse sections of the exposed earthworms passing through the body wall illustrated that there was a serious injury in epidermal tissue after an exposure of 28 days. These findings will provide a comprehensive understanding of toxicological effects of nZVI in a soil-earthworm system.

The anodic reaction of oxygen evolution reaction (OER), an important point for electrolysis, however, remains the obstacle due to its complicated reaction at electrochemical interfaces. Iridium oxide (IrO 2 ) is the only currently known 5d transition metal oxide possessing admirable OER activity. Tremendous efforts have been carried out to enhance the activity of iridium oxides. Unfortunately there lies a gap in understanding what factors responsible for the activity in doped IrO 2 or the novel crystal structure. Based on two metallic pyrochlores (Bi 2 Ir 2 O 7 and Pb 2 Ir 2 O 6.5 ) and IrO 2 . It has been found that there exists a strong correlation between the specific OER activity and IrO 6 coordination geometry. The more distortion in IrO 6 geometry ascends the activity of Ir sites, and generates activity order of Pb-Ir > IrO 2  > Bi-Ir. Our characterizations reveal that distorted IrO 6 in Pb-Ir induces a disappearance of J = 1/2 subbands in valence band, while Bi-Ir and IrO 2 resist this nature probe. The performed DFT calculations indicated the distortion in IrO 6 geometry can optimize binding strength between Ir-5d and O-2p due to broader d band width. Based on this insight, enhancement in OER activity is obtained by effects that change IrO 6 octahedral geometry through doping or utilizing structural manipulation with nature of distorted octahedral coordination.