The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included.

/pdf/anion-exchange-membranes-in-electrochemical-energy-systems-46uquenb56.pdf

Anion-exchange membranes in electrochemical energy systems

The development of low-cost, efficient, and stable electrocatalysts for the oxygen reduction reaction (ORR) is desirable but remains a great challenge. Herein, we made a highly reactive and stable isolated single-atom Fe/N-doped porous carbon (ISA Fe/CN) catalyst with Fe loading up to 2.16 wt %. The catalyst showed excellent ORR performance with a half-wave potential (E1/2) of 0.900 V, which outperformed commercial Pt/C and most non-precious-metal catalysts reported to date. Besides exceptionally high kinetic current density (Jk) of 37.83 mV cm−2 at 0.85 V, it also had a good methanol tolerance and outstanding stability. Experiments demonstrated that maintaining the Fe as isolated atoms and incorporating nitrogen was essential to deliver the high performance. First principle calculations further attributed the high reactivity to the high efficiency of the single Fe atoms in transporting electrons to the adsorbed OH species.

Isolated Single Iron Atoms Anchored on N-Doped Porous Carbon as an Efficient Electrocatalyst for the Oxygen Reduction Reaction

Spinels with the formula of AB2O4 (where A and B are metal ions) and the properties of magnetism, optics, electricity, and catalysis have taken significant roles in applications of data storage, biotechnology, electronics, laser, sensor, conversion reaction, and energy storage/conversion, which largely depend on their precise structures and compositions. In this review, various spinels with controlled preparations and their applications in oxygen reduction/evolution reaction (ORR/OER) and beyond are summarized. First, the composition and structure of spinels are introduced. Then, recent advances in the preparation of spinels with solid-, solution-, and vapor-phase methods are summarized, and new methods are particularly highlighted. The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches. This regulation can yield spinels with improved ORR/OER catalytic activities, which can furth...

Spinels: Controlled Preparation, Oxygen Reduction/Evolution Reaction Application, and Beyond

High-performance electrode materials are the key to advances in the areas of energy conversion and storage (e.g., fuel cells and batteries). In this Review, recent progress in the synthesis and electrochemical application of transition metal carbides (TMCs) and nitrides (TMNs) for energy storage and conversion is summarized. Their electrochemical properties in Li-ion and Na-ion batteries as well as in supercapacitors, and electrocatalytic reactions (oxygen evolution and reduction reactions, and hydrogen evolution reaction) are discussed in association with their crystal structure/morphology/composition. Advantages and benefits of nanostructuring (e.g., 2D MXenes) are highlighted. Prospects of future research trends in rational design of high-performance TMCs and TMNs electrodes are provided at the end.

/pdf/transition-metal-carbides-and-nitrides-in-energy-storage-and-33qhnc07u1.pdf

Transition Metal Carbides and Nitrides in Energy Storage and Conversion

Study on laser transmission interference characteristics based on atmospheric turbulent medium

/pdf/the-effects-of-initial-wedge-taper-on-area-balancing-2feepwum.pdf

The effects of initial wedge taper on area-balancing restoration of a fold-thrust belt

/pdf/correction-to-can-new-energy-demonstration-city-policy-3ov5prfj.pdf

Correction to: Can new energy demonstration city policy reduce carbon emissions? A quasi‑natural experiment from China

The combined effect of polyethylene (PE) microplastics and chromium (Cr(III)) on the scleractinian coral Acropora pruinosa (A. pruinosa) was investigated. The endpoints analysed in this study included the endosymbiont density, the chlorophyll a + c content, and the activity of enzymes involved in apoptosis (caspase-1, caspase-3), glycolysis (lactate dehydrogenase, LDH), the pentose phosphate pathway (glucose-6-phosphate dehydrogenase, G6PDH) and electron transfer coenzyme (nicotinamide adenine dinucleotide, NAD+/NADH). During the 7-day exposure to PE and Cr(III) stress, the endosymbiont density and chlorophyll content decreased gradually. The caspase-1 and caspase-3 activities increased in the high-concentration Cr(III) exposure group. Furthermore, the LDH and G6PDH activities decreased significantly, and the NAD+/NADH was decreased significantly. In summary, the results showed that PE and Cr(III) stress inhibited the endosymbiont energy metabolism enzymes and further led to endosymbiont apoptosis in coral. In addition, under exposure to the combination of stressors, when the concentration of Cr(III) remained at 1 × 10–2 mg/L, the toxic effects of heavy metals on the endosymbiont were temporarily relieved with elevated PE concentrations. In contrast, when coral polyps were exposed to 5 mg/L PE and increasing Cr(III) concentrations, their metabolic activities were seriously disturbed, which increased the burden of energy consumption. In the short term, the toxic effect of Cr(III) was more obvious than that of PE because Cr(III) exposure leads to endosymbiont apoptosis and irreversible damage. This is the first study to provide insights into the combined effect of microplastic and Cr(III) stress on the apoptosis and energy pathways of coral endosymbionts. This study suggested that microplastics combined with Cr(III) are an important factor affecting the apoptosis and energy metabolism of endosymbionts, accelerating the collapse of the balance between the coral host and symbiotic endosymbiont. 

https://www.researchsquare.com/article/rs-1350978/latest.pdf

Effects of microplastic combined with Cr(III) on apoptosis and energy pathway of coral endosymbiont

Phosphorus (P) is an important macronutrient in terrestrial ecosystems because it is involved in many biochemical reactions and limits plant growth. Existing studies have found that microbial communities regulate P cycling in soils, but little is known about biochemical mechanism. Specifically, it is not clear what factors drive P cycling in soils, and how microbial genes involved in the soil P cycling respond to water scarcity in desert ecosystems. Here, we conducted metagenomic analyses to reveal changes in microbial genes involved in the soil P cycling in an arid desert, and further evaluate microbial responses to P transformation along soil water content (SWC) gradient. The results showed that the relative abundance of P-starvation response regulation genes (phoR and phoP) exhibited an obviously changes along SWC gradient, indicating that they were affected by water constraint. Among the genes related to P uptake and transport, pstSCAB showed little change in the relative abundance while was not active toward water constraint. In contrast, P-mineralization genes (phn, ppx, and phoD) obviously increased with the decrease of SWC, reflecting that microorganism alleviated water constraint by promoting P mineralization. The “rhizosphere effect” clearly improved the role of several key genes of P cycling in the whole gene co-occurrence networks, indicating that plant rhizosphere environments promoted microbial P-assimilation capacity. The influence of SWC on microbial genes increased with the decrease of its value. pH and soil texture affected microbial genes in high water content environment, but not in lower water content environment. Inorganic phosphorus, mainly in the form of Ca10-P, played a crucial role in the adaptation of desert plants to resource limitation. Overall, microbial roles in regulating soil P cycling were jointly determined by “rhizosphere effect” and water constraint in arid desert. 

Xiaodong Yang

Papers

Study on laser transmission interference characteristics based on atmospheric turbulent medium

The effects of initial wedge taper on area-balancing restoration of a fold-thrust belt

Correction to: Can new energy demonstration city policy reduce carbon emissions? A quasi‑natural experiment from China

Effects of microplastic combined with Cr(III) on apoptosis and energy pathway of coral endosymbiont

Rhizosphere effect and water constraint jointly determined the roles of microorganism in soil phosphorus cycling in arid desert regions