Enhancing Hydrogen Evolution Electrocatalytic Performance in Neutral Media via Nitrogen and Iron Phosphide Interactions

It remains a challenge to develop efficient electrocatalysts in neutral media for hydrogen evolution reaction (HER) due to the sluggish kinetics and switch of the rate determining step. Although metal phosphides are widely used HER catalysts, their structural stability is an issue due to oxidization, and the HER performance in neutral media requires improvement. Herein, a new material, i.e., grapevine-shaped N-doped iron phosphide on carbon nanotubes, as an efficient HER catalyst in neutral media is developed. The optimized catalyst shows an overpotential of 256 mV at a large current density of 65 mA cm−2, which is even 10 mV lower than that of the commercial 20% Pt/C catalyst. The excellent performance of the catalyst is further studied by combined computational and experimental techniques, which proves that the interaction between nitrogen and iron phosphides can provide more efficient active structures and stabilize the metal phosphide electrocatalysts for HER

Biomass and Its Allocation in Relation to Temperature, Precipitation, and Soil Nutrients in Inner Mongolia Grasslands, China

<div><p>Aim</p><p>Understanding and predicting ecosystem functioning such as biomass accumulation requires an accurate assessment of large-scale patterns of biomass distribution and partitioning in relation to climatic and soil environments.</p><p>Methods</p><p>We sampled above- and belowground biomass from 26 sites spanning 1500 km in Inner Mongolian grasslands, compared the difference in aboveground, belowground biomass and below-aboveground biomass ratio (AGB, BGB, and B/A, respectively) among meadow steppe, typical steppe, and desert steppe types. The relationships between AGB, BGB, B/A and climatic and soil environments were then examined.</p><p>Results</p><p>We found that AGB and BGB differed significantly among three types of grasslands while B/A did not differ. Structural equation model analyses indicated that mean annual precipitation was the strongest positive driver for AGB and BGB. AGB was also positively associated with soil organic carbon, whereas B/A was positively associated with total soil nitrogen.</p><p>Conclusions</p><p>These results indicated that precipitation positively influence plant production in Inner Mongolian grasslands. Contrary to the prediction from the optimal partitioning hypothesis, biomass allocation to belowground increased with soil total nitrogen, suggesting that more productive sites may increase belowground allocation as an adaptive strategy to potentially high fire frequencies.</p></div

Results of structural equation models for: a) aboveground biomass (AGB), b) belowground biomass (BGB), and c) belowground to aboveground biomass ratio (B/A).

<p>Each arrow represents a direct linear causal relationship. The arcs show the correlation between two variables. Values on arrows are path coefficients and on arcs are standardized correlation coefficients. Italic values indicate the coefficients are significant at <i>P</i><0.05 (*), <i>P</i><0.01 (**), and <i>P</i><0.001 (***). The coefficients that are not statistically significant are shown by dashed arrows. All values are log-log transformed.</p

Relationship between aboveground biomass (AGB) and belowground biomass (BGB) (<i>n = </i>26).

<p>The fitted regression is <i>y</i> = 1.064+0964<i>x</i> (<i>R</i>² = 0.77, <i>P</i><0.001).</p

Tailoring of Fe/MnK-CNTs Composite Catalysts for the Fischer–Tropsch Synthesis of Lower Olefins from Syngas

Iron-catalyzed conversion of coal/biomass-derived syngas directly to lower olefins through Fischer–Tropsch synthesis (i.e., FTO) is a sustainable and short-flow process. Herein, effects of Mn and K promoter loadings on FTO performance over the Fe-based catalyst supported on the promoter-adjustable carbon nanotubes (Fe/MnxKy-CNTs) are systematically studied. Several MnxKy-CNTs are prepared by the treatment of CNTs using aqueous KMnO4 solution via a redox reaction, where promoter loadings are tailored by changing the aqueous KMnO4 solution concentration and water amount for sample washing. FTO performance of these catalysts suggests that the increase in Mn and K loadings shows the enhanced lower olefins selectivity but suppressed activity. The resultant Fe/Mn16.5K1.2-CNTs exhibit the highest lower olefins yield. Further increasing K promoter content leads to slightly enhanced activity to lower olefins but dramatically suppressed CH4 formation and enhanced chain growth. Moreover, appropriate precarburization temperature can facilitate the activity and selectivity toward lower olefins formation

Standardized direct effect, indirect effect, and total effect of mean annual temperature (MAT), mean annual precipitation (MAP), soil organic carbon (SOC), soil total nitrogen, and soil pH on aboveground biomass (AGB), belowground biomass (BGB), and below- to aboveground biomass ratio (B/A).

<p>Significant effects are indicated at *(<i>P</i><0.05), **(<i>P</i><0.01), and ***(<i>P</i><0.001).</p><p>Note: full table is presented in Table S1, Table S2 and Table S3 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069561#pone.0069561.s001" target="_blank">File S1</a>.</p

The aboveground biomass (AGB), belowground biomass (BGB), total biomass (TB) and belowground to aboveground biomass ratio (B/A) among three grassland types in Inner Mongolia (mean ±1 SE).

<p>Within the same columns, values with different superscripts letters (a, b, c) indicate significant difference (α <0.05) between grassland types.</p

The distribution of sample sites in Inner Mongolia, China.

<p>The distribution of sample sites in Inner Mongolia, China.</p

Optimization of polyhydroxybutyrate (PHB) production by excess activated sludge and microbial community analysis

In this study, a high value-added and biodegradable thermoplastic, polyhydroxybutyrate (PHB), was produced by excess activated sludge. The effects of the nutritional condition, aeration mode, sodium acetate concentration and initial pH value on PHB accumulation in the activated sludge were investigated. The maximum PHB content and PHB yield of 67.0% (dry cell weight) and 0.740 gCOD gCOD(-1) (COD: chemical oxygen demand), respectively, were attained by the sludge in the presence of 6.0 g L(-1) sodium acetate, with an initial pH value of 7.0 and intermittent aeration. The analysis of the polymerase chain reaction (PCR)-denaturing gradient-gel-electrophoresis (DGGE) sequencing indicated that the microbial community of the sludge was significantly different during the process of PHB accumulation. Three PHB-accumulating microorganisms, which were affiliated with the Thauera, Dechloromonas and Competibacter lineages, were found in the excess activated sludge under different operating conditions for PHB accumulation. (C) 2010 Elsevier B.V. All rights reserved.National Natural Science Foundation of China[30700020]; Science and Technology Program of Fujian Province, China[2008Y0060]; Science and Technology Program of Xiamen of Fujian Province, China[3502Z20073005]; Natural Science Foundation for Youths of Fujian Province, China[2010J05121