Application of Rice Husk Biochar for Achieving Sustainable Agriculture and Environment

This paper critically reviewed the current knowledge and challenges of rice husk biochar(RHB)production and its effects on soil properties,plant growth,immobilization of heavy metals,reduction of nutrient leaching and mitigation of greenhouse gas emissions.The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro-industrial wastes.RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio,which suggests the presence of higher aromatic carbon compounds.The increase of pyrolysis temperature also results in production of RHBs with higher ash content,lower yield and higher surface area.RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions.Although it depends on soil type,RHB application can improve soil organic carbon content,cation exchange capacity,available K concentration,bulk density and microbial activity.The effect of RHB on soil aggregation mainly depends on soil texture.The growth of different crops is also enhanced by application of RHB.RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability.RHB application shows a significant capacity in reduction of nitrate leaching,although its magnitude depends on the biochar application rate and soil biogeochemical characteristics.Use of RHB,especially in paddy fields,shows a promising mitigation effect on greenhouse gas(CH4,CO2 and N2O)emissions.Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time,its performance for specific applications(e.g.carbon sequestration,pH amendment)can be manipulated by adjusting the pyrolysis temperature.More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.

佛山地区存留自然林和存留人工林的土壤无机磷组分(英文)

为探讨热带亚热带森林,尤其城市及其周边地区残存森林土壤磷的有效性,对佛山地区14个残存林(7个自然林和7个人工林)的0～3 cm和3～23 cm矿质土壤的P有效性进行研究。结果表明,铁结合态无机P和还原剂可溶解无机P是土壤无机P的主要组分。在0～3 cm矿质层中,自然林土壤铝结合态无机P、Bray 1提取无机P和总无机P含量显著高于人工林;而在3～23 cm矿质土层中,自然林土壤钙结合态无机P含量显著高于人工林。其它土壤营养指标在自然林和人工林间差异不显著。相关分析结果表明,土壤有机质含量与钙结合态无机P除外的其它无机P组分含量均成显著正相关。聚类分析结果表明14个残存林土壤P有效性可分成3组,整体上人工林土壤P有效性比自然林低。这有助于认识城市化影响下城市及其周边地区残存森林土壤营养状况及加强养分管理。

Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration.Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density,species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broadleaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests.The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests.

Nanoporous SiO_x coated amorphous silicon anode material with robust mechanical behavior for high-performance rechargeable Li-ion batteries

Silicon is a promising anode material for rechargeable Li-ion battery (LIB) due to its high energy density and relatively low operating voltage. However, silicon based electrodes suffer from rapid capacity degradation during electrochemical cycling. The capacity decay is predominantly caused by (i) cracking due to large volume variations during lithium insertion/extraction and (ii) surface degradation due to excessive solid electrolyte interface (SEI) formation. In this work, we demonstrate that coating of a-Si thin film with a Li-active, nanoporous SiOx layer can result in exceptional electrochemical performance in Li-ion battery. The SiOx layer provides improved cracking resistance to the thin film and prevent the active material loss due to excessive SEI formation, benefiting the electrode cycling stability. Half-cell experiments using this anode material show an initial reversible capacity of 2173 mAh g^-1 with an excellent coulombic efficiency of 90.9%. Furthermore, the electrode shows remarkable capacity retention of ~97% after 100 cycles at C/2 charging rate. The proposed anode architecture is free from Liinactive binders and conductive additives and provides mechanical stability during the charge/discharge process.

α-Fe_2O_3 nanoplates with superior electrochemical performance for lithium-ion batteries

On account of the high theoretical capacity, high corrosion resistance, environmental benignity, abundant availability and low cost, the research on a-Fe_2O_3 has been gradually fastened on as promising anodes materials toward lithium-ion batteries(LIBs). A high-performance anode for LIBs based on α-Fe_2O_3 nanoplates have been selectively prepared. The α-Fe_2O_3 nanoplates can be synthesized with iron ionbased ionic liquid as iron source and template. The α-Fe_2O_3 nanoplates as the anode of LIBs can display high capacity of around1950 mAh g^(-1) at 0.5 A g^(-1) which have exceeded the theoretical capacity of α-Fe_2O_3. On account of unique nanoplate structures and gum arabic as binder, the α-Fe_2O_3 nanoplates also exhibit high rate capability and excellent cycling performance.

Layered Fe(Ⅲ) doped TiO_2 thin-film electrodes for the photoelectrocatalytic oxidation of glucose and potassium hydrogen phthalate

Four types of TiO 2 thin-film electrodes were fabricated from TiO 2 and Fe(III) doped TiO 2 sols using a layer-by-layer dip-coating technique. Electrodes fabricated were TF (pure TiO 2 surface, Fe(III)-TiO 2 bottom layer), FT (Fe(III)-TiO 2 surface, pure TiO 2 bottom layer), TT (both layers pure TiO 2 ) and FF (both layers Fe(III)-TiO 2 ). The photoelectrochemical behavior of these electrodes was characterized using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and steady-state photocurrent measurements in aqueous 0.1 mol L –1 NaNO 3 containing varying concentrations of glucose or potassium hydrogen phthalate (KHP). EIS and LSV results revealed that exciton separation efficiency followed the sequence of TF﹥TT﹥FT > FF. Under a constant potential of +0.3 V, steady-state photocurrent profiles were recorded with varying organic compound concentrations. The TF electrode possessed the greatest photocatalytic capacity for oxidizing glucose and KHP, and possessed a KHP anti-poisoning effect. Enhanced photoelectrochemical performance of the TF electrode was attributed to effective exciton separation because of the layered TF structure.

Hydrogenation of nanostructured semiconductors for energy conversion and storage

Nanostructured semiconductors have been researched intensively for energy conversion and storage applications in recent decades.Despite of tremendous findings and achievements,the performance of the devices resulted from the nanomaterials in terms of energy conversion efficiency and storage capacity needs further improvement to become economically viable for subsequent commercialization.Hydrogenation is a simple,efficient,and cost-effective way for tailoring the electronic and morphological properties of the nanostructured materials.This work reviews a series of hydrogenated nanostructured materials was produced by the hydrogenation of a wide range of nanomaterials.These materials with improved inherent conductivity and changed characteristic lattice structure possess much enhanced performance for energy conversion application,e.g.,photoelectrocatalytic production of hydrogen,and energy storage applications,e.g.,lithium-ion batteries and supercapacitors.The hydrogenation mechanisms as well as resultant properties responsible for the efficiency improvement are explored in details.This work provides guidance for researchers to use the hydrogenation technology to design functional materials.

Sustainable engineering of TiO_(2)-based advanced oxidation technologies:From photocatalyst to application devices

In recent years,photocatalysis(PC)and photoelectrocatalysis(PEC)technologies have shown great promise as low-cost,environmentally friendly,and sustainable strategies in addressing the issues of energy shortages and environmental pollution,which has become a research hotspot.Titanium dioxide(TiO_(2))-based PC and PEC are the most promising sustainable technologies for advanced oxidation applications.Due to its inherent characteristics,including high oxidation ability,low price,and stability,TiO_(2)photocatalyst has been widely studied and used in different scales for numerous decades.For practical applications in these areas,the engineering of the photocatalysts and the design of the PC and PEC devices must be both environmentally and economically sustainable.On the one hand,for the engineering of the photocatalysts,the photocatalyst shall be able to deliver the following characteristics,including large specific surface area,high absorption of light,rapid and low-cost separation and regeneration,and high stability.On the other hand,the design of the PC and PEC devices shall facilitate high in energy utilization and catalytic efficiency,and low in building and operational cost.This work covers the reaction mechanism of TiO_(2)-based PC and PEC technologies,sustainable design,and preparation of TiO_(2)photocatalysts as well as sustainable design in PC and PEC devices for wastewater treatment,sensing,and water splitting.Finally,we provide some critical perspectives on the future development of TiO_(2)-based PC and PEC technology.

Photoelectrocatalytic activity of an ordered and vertically aligned TiO2 nanorod array/BDD heterojunction electrode

Rutile TiO_2 nanorod(TiNR) arrays were fabricated on a boron-doped diamond(BDD) substrate by a simple hydrothermal synthesis method. A fluorine-doped tin oxide(FTO) electrode grown with TiNR arrays was also prepared using the same technology for comparison. Field-emission scanning electron microscopy results show that oriented TiNR arrays can grow vertically on the surface of BDD and FTO electrodes. TiNR arrays grown on both electrodes had the same length(3 μm). In comparison with the TiNR/FTO electrode, the TiNR/BDD electrode demonstrated a higher photoelectrocatalytic activity for the degradation of water and organic compounds, which is mostly attributed to the formation of a p-n heterojunction between the TiNR arrays and BDD at high potential, apart from the density of TiNR. A linear relationship between the photoelectrocatalytic current and the organic concentration can be observed on both electrodes. However, the linear range between net photoelectrocatalytic current values and organic compound concentrations for the TiNR/BDD electrode are much greater than those for the TiNR/FTO electrode, which makes the TiNR/BDD electrode a versatile material for the photocatalytic degradation and sensing of organic compounds.

Environmental and spatial contributions to seedling and adult tree assembly across tropical,subtropical and subalpine elevational gradients

Aims Quantifying the relative importance of the mechanisms that drive community assembly in forests is a crucial issue in community ecol-ogy.The present study aims to understand the ways in which niche-based and spatially based processes influence community assembly in areas in different climatic conditions and how these processes change during the transition from seedling to adult.Methods In this study,we investigated how taxonomic and phylogenetic beta diversity in seedling and adult stages of forest trees change across three elevational transects in tropical,subtropical and subalpine for-ests in Southwest China,and the relationships of these changes to the environment and inter-site distances.We quantified the relative contribution of environmental conditions and spatial distribution to taxonomic and phylogenetic beta diversity of both seedling and adult life stages along each elevational transect.We also quantified the taxonomic and phylogenetic similarity between seedlings and adult trees along elevations.Important Findings Taxonomic and phylogenetic beta diversity of both seedlings and adult trees increased with an increase in both environmental distance and spatial distance in all three transects.On both taxonomic and phylo-genetic levels,the effects of environmental filtering and spatial dispos-ition varied between life stages and among forest types.Phylogenetic similarity between seedlings and adult trees increased with elevation,although the taxonomic similarity did not show clear elevational pat-terns.Our results suggest that the relative contribution of niche-based and space-based processes to taxonomic and phylogenetic assem-blages varies across major plant life stages and among forest types.Our findings also highlight the importance of ontogenetic stages for fully understanding community assembly of long-lived tree species.

Scaffold-regulation buffered MoS_(2)anode kinetics for high-performance Na-/K-ion storage

Designing a highly conductive scaffold with unique function has great significance in elevating the stor-age properties of molybdenum sulfide(MoS_(2))for sodium-and potassium-ion batteries.Herein,we show that forming a three-dimensional(3D)highly conductive dual backbone that consists of titanium nitride nanowires(TiN)coated on 3D carbon fiber(CF)could suppress the poor conductivity of MoS_(2).Theo-retical calculations predict that both TiN and CF boost the electronic conductivity,while the MoS_(2)will promote high ionic adsorption owing to the suitable adsorption energy.The as-prepared CF@TiN/MoS_(2),with mass loading up to 12.5 mg cm^(−2),achieves a high areal capacity of up to 5.40 mAh cm^(−2)under the current density of 0.6 mA cm^(−2)for sodium storage.The excellent performance of the hybrid can be attributed to buffer and conductivity enhancer features,allowing Na-ion to directly have contact with the CF@TiN/MoS_(2)hybrid.A series of electrochemical analyses including cyclic voltammetry and symmetric cell analyses affirm the significant improvement in transport kinetics.More importantly,the CF@TiN/MoS_(2)also achieves a high areal capacity of 3.29 mAh cm^(−2)under the current density of 0.3 mA cm^(−2)as anode material for potassium ion batteries(PIBs),demonstrating that the scaffold-regulated strategy is a feasible strategy to enhance the kinetics of MoS_(2)-based anodes for secondary-ion batteries and beyond.

Microporous bamboo biochar for lithium-sulfur batteries

Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur （Li-S） batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur （BC-S） nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency （995%）. This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.

Rutile TiO2 Microspheres with Exposed Nano-Acicular Single Crystals for Dye-Sensitized Solar Cells

Uniquely structured rutile TiO2 microspheres with exposed nano-acicular single crystals have been successfully synthesized via a facile hydrothermal method. After calcination at 450 ℃ for 2 h, the futile TiO2 microspheres with a high surface area of 132 m2/g have been utilized as a light harvesting enhancement material for dye-sensitized solar cells （DSSCs）. The resultant DSSCs exhibit an overall light conversion efficiency of 8.41% for TiO2 photoanodes made of futile TiO2 microspheres and anatase TiO, nanoparticles （mass ratio of 1：1）, significantly higher than that of pure anatase TiO2 nanoparticle photoanodes of similar thickness （6.74%）. Such a significant improvement in performance can be attributed to the enhanced light harvesting capability and synergetic electron transfer effect. This is because the photoanodes made of futile TiO2 microsphere possess high refractive index which improves the light utilisation efficiency, suitable microsphere core sizes （450-800 nm） to effectively scatter visible light, high surface area for dye loading, and synergetic electron transfer effects between nanoparticulate anatase and nano-acicular futile single crystals phases giving high electron collection efficiency.

High-performance aqueous symmetric sodium-ion battery using NASICON-structured Na2VTi（PO4）3

A high-safety and low-cost route is important in the development of sodium-ion batteries, especially for large-scale stationary battery systems. An aqueous sodium-ion battery is demonstrated using a single NASICON-structured Na2VTi（PO4）3 material with the redox couples of V4＋/V3＋ and Ti4＋/Ti3＋ working on the cathode and anode, respectively. The symmetric full cell fabricated based on the bi-functional electrode material exhibits a well-defined voltage plateau at ~ 1.2 V and an impressive cycling stability with capacity retention of 70% exceeding 1,000 cycles at 10C （1C = 62 mA.g-1）. This study provides a feasible strategy for obtaining high-safety and low-cost rechargeable batteries using a single active material in aqueous media.

Graphene-Based Sulfur Composites for Energy Storage and Conversion in Li-S Batteries

There are growing research interests in developing high-performance energy storage systems to meet the demands for large-scale and sustainable energy storage. The lithium-sulfur （Li-S） batteries have drawn numerous attentions due to their exceptionally high energy density compared with other batteries. However, achieving the high capacities with long-term cycle stability and retaining an essentially high sulfur loading remains a tremendous chal- lenge for the designs of Li-S batteries. Graphene is regarded as a very suitable and promising addition to the com- positions for Li-S batteries due to its unique two dimensional （2D） structure, high conductivity and superior me- chanical flexibility. Besides, the functional groups of graphene surface can be tuned flexibly to immobilize the S/Li2Sx on the graphene surface during the cycling process. In this review, the development of graphene-sulfur composites and their applications in Li-S batteries are discussed. The attempts are also devoted to the synthesis approaches of various graphene-based sulfur composites, the graphene-sulfur interaction and the impacts on the elec- trochemical performances as well as the major issues of Li-S batteries.

{001} facets dominated anatase TiO_(2) : Morphology, formation/etching mechanisms and performance

Controllable growth of anatase TiO_(2)crystals with exposed high reactive crystal facets has aroused great attention in the fields of science and technology due to their unique structure-dependent properties.Recently,much effort has been paid to synthesize anatase TiO_(2)crystals with exposed high reactive{001}facets.Herein,we review the recent progress in synthesizing{001}facets dominated anatase TiO_(2)crystals with different morphologies by various synthetic methods.Furthermore,our review is mainly focused on the formation/etching mechanisms of{001}facets dominated anatase TiO_(2)crystals based on our and other studies.The extensive application potentials of the anatase TiO_(2)crystals with exposed{001}facets have been summarized in this review such as photocatalysis,photoelectrocatalysis,solar energy conversion,lithium ion battery,and hydrogen generation Based on the current studies,we give some perspectives on the research topic.We believe that this comprehensive review on anatase TiO_(2)crystals with high reactive{001}facets can further promote the relative research in this field.

Adélie penguins and temperature changes in Antarctica: a long-term view

During the summer months,Adélie penguins represent the dominant biomass of terrestrial Antarctica.Literally millions of individuals nest in ice-free areas around the coast of the continent.Hence,these modern populations of Adélie penguins have often been championed as an ideal biological indicator of ecological and environmental changes that we currently face.In addition,Adélie penguins show an extraordinary record of sub-fossil remains,dating back to the late Pleistocene.At this time,temperatures were much lower than now.Hence,this species of­fers unique long-term information,at both the genomic and ecological levels,about how a species has responded to climate change over more than 40000 years.