A photoactive process cascaded electrocatalysis for enhanced methanol oxidation over Pt-MXene-TiO2 composite

Highly efficient photo-assisted electrocatalysis for methanol oxidation reaction(MOR)realizes the conversion of solar and chemical energy into electric energy simultaneously.Here we report a Pt-MXene-TiO2 composite for highly efficient MOR via a photoactive cascaded electro-catalytic process.With light(UV and visible light)irradiation,MXene-TiO2 serves as the photo active centre(photoinduced hole)to activate the methanol molecules,while Pt particles are the active centre for the following electro-catalytic oxidation of those activated methanol molecules.Pt-MXene-TiO2 catalyst exhibits a lower onset potential(0.33 V)and an impressive mass activity of 2,750.42 mA·mg^−1 Pt under light illumination.It represents the highest MOR activity ever reported for photo-assisted electrocatalysts.Pt-MXene-TiO2 also shows excellent CO tolerance ability and stability,in which,after long-term(5,000 s)reaction,still keeps a high mass activity of 1,269.81 mA·mg−1Pt(62.66%of its initial activity).The photo-electro-catalytic system proposed in this work offers novel opportunities for exploiting photo-assisted enhancement of highly efficient and stable catalysts for MOR.

Dynamic reconfiguration for TEG systems under heterogeneous temperature distribution via adaptive coordinated seeker

A thermoelectric generation(TEG)system has the weakness of relatively low thermoelectric conversion efficiency caused by heterogeneous temperature distribution(HgTD).Dynamic reconfiguration is an effective technique to improve its overall energy efficiency under HgTD.Nevertheless,numerous combinations of electrical switches make dynamic reconfiguration a complex combinatorial optimization problem.This paper aims to design a novel adaptive coordinated seeker(ACS)based on an optimal configuration strategy for large-scale TEG systems with series-paral-lel connected modules under HgTDs.To properly balance global exploration and local exploitation,ACS is based on'divide-and-conquer'parallel computing,which synthetically coordinates the local searching capability of tabu search(TS)and the global searching capability of a pelican optimization algorithm(POA)during iterations.In addition,an equivalent re-optimization strategy for a reconfiguration solution obtained by meta-heuristic algorithms(MhAs)is proposed to reduce redundant switching actions caused by the randomness of MhAs.Two case studies are carried out to assess the feasibility and superiority of AcS in comparison with the artificial bee colony algorithm,ant colony optimization,genetic algorithm,particle swarm optimization,simulated annealing algorithm,TS,and POA.Simulation results indicate that ACS can realize fast and stable dynamic reconfiguration of a TEG system under HgTDs.In addition,RTLAB platform-based hardware-in-the-loop experiments are carried out to further validate the hardware implemen-tation feasibility.

Increased nitrogen fertilization inhibits the biocontrol activity promoted by the intercropping partner plant

The examination of the compatibility between agricultural practices and biocontrol activities is crucial for establishing an efficient,eco-friendly,and sustainable pest management program.In this study,we examined the population dynamics of two specialist aphids,the English grain aphid(Sitobion avenae)on potted wheat and the pea aphid(Acyrthosiphon pisum)on potted alfalfa,as well as the biocontrol activity of a generalist predator,the harlequin ladybird beetle(Harmonia axyridis).We investigated their responses to the presence of the intercropping partner plant species(alfalfa and wheat,respectively)through plant volatiles or visual cues at three nitrogen fertilizer levels in a greenhouse.In the absence of the predator,the English grain aphid population growth rate increased significantly with increasing nitrogen levels,whereas the pea aphid population increased significantly more slowly in response to high nitrogen levels.The English grain aphid and pea aphid population dynamics were unaffected by the presence of the intercropping partner.However,the presence of the intercropping partner enhanced the control of both aphid populations by the harlequin ladybird beetle.Increasing nitrogen fertilizer levels decreased the predation rates,which were otherwise increased by the intercropping partner.The beneficial effects of the intercropping partner were eventually non-existent at the highest nitrogen level tested.These results imply that the interaction between the presence of intercropping partner and the nitrogen fertilizer application affects the biocontrol activity of the natural enemies of insect pests.Thus,the compatibility between agricultural intensification and biocontrol strategies in integrated pest management programs need to be investigated.

The stomata frontline of plant interaction with the environment-perspectives from hormone regulation

Plants have evolved elaborate mechanisms to perceive and integrate signals from various environmental conditions. On leaf surface, stomata formed by pairs of guard cells mediate gas exchange, water transpiration as well as function in response to abiotic and biotic stresses. Stomatal closure could be induced by drought, salt, pathogen and other adverse conditions. This constitutes an instant defense response to prevent further damage to plants. Abscisic acid （ABA） is a major plant hormone involved in stress responses. Stress-activated ABA synthesis causes stomatal closure and prevents opening to reduce water loss and cell dehydration. Key regulatory receptor complex and other important components in the ABA signaling pathway have been identified. However, our knowledge of ABA signal transduction in guard cells is far from complete. Jasmonates are a group of phytohormones generally known to be important for plant defense against insects and necrotrophic pathogens. The increased levels of methyl jasmonate （MeJA） induced by herbivory and pathogen invasion show a similar effect on stomatal movement associated with ROS production as ABA. Investigation of guard cell signaling networks involving the two important phytohormones is significant and exciting. Information about protein and metabolite components and how they interact in guard cells is lacking. Here we review recent advances on hormone signaling networks in guard cells and how the networks integrate environmental signals to plant physiological output.

Tetra-EDOT substituted 3D electrochromic polymers with lower band gaps

A couple of novel electrochromic materials poly(2,3,4,5-tetrakis(2,3-hydrothieno[3,4-b]dixin-5-yl)-1-methyl-1H-pyrrole)(P(t-EDOT-mPy))and poly(5,5',5",5'"-(thiophene-2,3,4,5-tetrayl)tetrakis(2,3-dihydrothieno[3,4-b][1,4]dioxine))(P(t-EDOTTh))are electrodeposited via multi-position polymerization of their tetra-EDOT substituted monomers t-EDOT-mPy and t-EDOT-Th,respectively.Compared with the linear 2D structured poly(thiophene)(E_g=2.2 eV)and poly(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophene)(E_g=1.7eV),P(t-EDOT-Th)(E_g=1.62eV)has the lowest band gap.Hence,we speculate that the band gaps of the two polymers,having 3D structures,are decreased in contrast to non-substituted polymers or bi-EDOT substituted polymers,thiophene and 1-methyl-1H-pyrrole.The results indicated that P(t-EDOT-Th)thin films are more stable and show higher transmittance amid two polymers,which may find their utilization in organic optoelectronics.

Aligning Fe_(2)O_(3)photo-sheets on TiO_(2)nanofibers with hydrophilic and aerophobic surface for boosting photoelectrochemical performance

Photoelectrochemical(PEC)nanomaterials are critical to producing clean oxygenation or value-added chemical production by utilizing sustainable solar energy,but are always limited by simultaneous integration of architectural engineering and electronic regulation in one structure.Directed by density functional theory(DFT)calculations and finite element analysis(FEA),the bioinspired ivy-like Fe_(2)O_(3)heterostructures with enriched oxygen defects on TiO_(2)nanofibers are designed for boosting PEC performances.Ivy-like Fe_(2)O_(3)photo-sheets remarkably enhanced the light harvesting by multiple light-mater interactions.The oxygen vacancies on Fe_(2)O_(3)photo-sheets could aid the photons catching and promote the reactivity at active sites.More importantly,demonstrated by a well-designed dynamic observation,the abundant tip-edges within ivy-like Fe_(2)O_(3)photo-sheets enabled the surface of heterostructure with hydrophilic and aerophobic properties.The functionalized surface allowed the rapid desorption of produced bubbles and thus ensured a high density of unoccupied active sites for electrolyte accessing.Featured by these attributes,the Fe_(2)O_(3)@TiO_(2)nanofibers delivered an excellent photocurrent of 40.8 mA/mg,high donor density(1.2×10^(18)cm^(−3)),and rapid oxygen production rate(1 mmol/(L∙h)).This work demonstrates a new strategy on nano-structural design for enhancing light-harvesting and making a hydrophilic/aerophobic surface on low-dimensional oxide nanomaterial,holding great potential on designing high-performance PEC devices for producing survival source gas,carbon-neutral fuel,and valuedchemicals.

Molecular engineering tuning optoelectronic properties of thieno[3,2-b]thiophenes-based electrochromic polymers

Thieno[3,2-b]thiophene(TT)monomers end-capped with 3,4-ethylenedioxythiophene(EDOT)moieties are electropolymerized to formπ-conjugated polymers with distinct electrochromic(EC)properties.Steric and electronic factors(electron donor and acceptor substituents)in the side groups of the TT core,as well as the structure of the polymer backbone strongly affect the electrochemical and optical properties of the polymers and their electrochromic characteristics.The studied polymers show low oxidation potentials,tunable from-0.78 to+0.30 V(vs.Fc/Fc^+)and the band gaps from 1.46 to 1.92 eV and demonstrate wide variety of color palettes in polymer films in different states,finely tunable by structural variations in the polymer backbone and the side chains.EC materials of different colors in their doped/dedoped states have been developed(violet,deep blue,light blue,green,brown,purple-red,pinkish-red,orange-red,light gray,cyan and colorless transparent).High optical contrast(up to 79%),short response time(0.57-0.80 s),good cycling stability(up to 91%at 2000 cycles)and high coloration efficiency(up to 234.6 cm2C^(-1))have been demonstrated and the influence of different factors on the above parameters of EC polymers have been discussed.