Water-resistant organic thermoelectric generator with >10μW output

Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability of n-type materials is essential to ensuring large temperature differences between device terminals and ambient stability.With the aim of improving the long-term stability of the n-type operation of carbon nanotubes(CNTs)in air and water,this study uses cationic surfactants,such as octylene-1,8-bis(dimethyldodecylammonium bromide)(12-8-12),a gemini surfactant,to stabilize the nanotubes in a coating,which retains the n-doped state for more than 28 days after exposure to air and water in experiments.TEGs with 10 p-n units of 12-8-12/CNT(n-type)and sodium dodecylbenzene sulfonate/CNT(p-type)layers are manufactured,and their water stability is evaluated.The initial maximum output of 16.1μW(75 K temperature difference)is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation.The excellent stability of these CNT-based TEGs makes them suitable for underwater applications,such as battery-free health monitoring and information gathering systems,and facilitates the development of soft electronics.

Advanced heterostructure of Pd nanosheets@Pt nanoparticles boosts methanol electrooxidation

Heterostructures have emerged as elaborate structures to improve catalytic activity owing to their combined surface and distinct inverse interface.However,fabricating advanced nanocatalysts with facetdependent interface remains an unexploited and promising area.Herein,we render the controlled growth of Pt nanoparticles(NPs)on Pd nanosheets(NSs)by regulating the reduction kinetics of Pt^(2+)with solvents.Specifically,the fast reduction kinetic makes the Pt NPs uniformly deposited on the Pd NSs(U-Pd@Pt HS),while the slow reduction kinetic leads to the preferential growth of Pt NPs on the edge of the Pd NSs(E-Pd@Pt HS).Density functional theory calculations demonstrate that Pd(111)-Pt interface in U-Pd@Pt HS induces the electron-deficient status of Pd substrates,triggering the d-band center downshift and amplifying the Pd-Pt intermetallic interaction.The synergy between the electronic effect and interfacial effect facilitates the removal of poisonous intermediates on U-Pd@Pt HS.By virtue of the Pd NSs@Pt NPs interface,the heterostructure achieves exceptional methanol oxidation reaction activity as well as improved durability.This study innovatively proposes heterostructure engineering with facetdependent interfacial modulation,offering instructive guidelines for the rational design of versatile heterocatalysts.

Hierarchical AgAu alloy nanostructures for highly efficient electrocatalytic ethanol oxidation

The ethanol oxidation reaction is a significant anodic reaction for direct alcohol fuel cells.The most commonly used catalysts for this reaction are Pt‐based materials;however,Pt‐based electrocatalysts cause carbon monoxide poisoning with intermediates before the complete transformation of alcohol to CO_(2).Herein,we present hierarchical AgAu bimetallic nanoarchitectures for ethanol electrooxidation,which were fabricated via a partial galvanic reduction reaction between Ag and HAuCl_(4).The ethanol electrooxidation performance of the optimal AgAu nanohybrid was increased to 1834 mA mg^(‒1),which is almost 10 times higher than that of the pristine Au catalyst(190 mA mg^(‒1))in alkaline solutions.This was achieved by introducing Ag into the Au catalyst and controlling the time of the replacement reaction.The heterostructure also presents a higher current density than that of commercial Pt/C(1574 mA mg^(‒1)).Density functional theory calculations revealed that the enhanced activity and stability may stem from unavoidable defects on the surface of the integrated AgAu nanoarchitectures.Ethanol oxidation reactions over these defects are more energetically favorable,which facilitates the oxidative removal of carbonaceous poison and boosts the combination with radicals on adjacent Au active sites.

Near-infrared response Pt-tipped Au nanorods/g-C_(3)N_(4) realizes photolysis of water to produce hydrogen

The search for a suitable cocatalyst for graphitic carbon nitride(g-C_(3)N_(4)) to realize efficient photocatalytic hydrogen(H_(2)) evolution has been regarded as one of the most valid tactics to alleviate energy crisis.Herein,a ternary Pt-tipped Au nanorods(Pt-Au)/g-C_(3)N_(4) heterostructure is constructed,which shows excellent H_(2) production performance in visible and near-infrared(NIR) region,especially in NIR region with a rate of 51.6 μmol g^(-1)h^(-1).Therein,not only is the optical absorption ability of g-C_(3)N_(4) broadened,the light absorption range is also extended to NIR region through introduction of Pt-Au architectures.Besides,analysis of the hot electrons generated in energy relaxation of plasmon indicates hot electron transfers fromexcited Au nanorods to Pt nanoparticles,resulting in H_(2) evolution.Compared with bare g-C_(3)N_(4),the superior photocatalytic activity could be attributed to the surface plasmon resonance effect(SPR) of Au nanorods and the electron-sink function of Pt nanoparticles.This work provides an insight into the improvement of photocatalytic performance via combination of NIR-responsive plasmon metal with photocatalysts.

Advances in engineering RuO_(2) electrocatalysts towards oxygen evolution reaction

Water electrolysis technology holds the perfect promise of the hydrogen production,yet control of efficiency and rate of water electrolysis greatly relies on the availability of high-performance electrode materials for kinetic-sluggish oxygen evolution reaction(OER).Accordingly,substantial endeavors have been made to explore advanced electrode materials over the past decade.Recently,RuO_(2) and RuO_(2)-based materials have been demonstrated to be promising for OER due to their remarkable electrocatalytic activity and pH-universal application.Herein,the great achievements and progresses of this flourishing spot are comprehensively reviewed,which are started by a general description of OER to understand the reaction mechanism in detail.Subsequently,the key advantages and issues of RuO_(2) towards OER are also introduced,followed by proposing many advanced strategies for further promoting the electrocatalytic OER performance of RuO_(2).Finally,the daunting challenges and future progresses of RuO_(2) electrocatalysts toward practical water oxidation are highlighted,aiming to provide guidance for the fabrication of desirable RuO_(2)-based electrocatalysts toward OER.

Green Route for Fabrication of Water-Treatable Thermoelectric Generators

Since future energy harvesting technologies require stable supply and high-efficiency energy conversion,there is an increasing demand for high-performance organic thermoelectric generators(TEGs)based on waterproof thermoelectric materials.The poor stability of n-type organic semiconductors in air and water has proved a roadblock in the development of reliable thermoelectric power generators.We developed a simple green route for preparing n-type carbon nanotubes(CNTs)by doping with cationic surfactants and fabricated films of the doped CNTs using only aqueous media.The thermoelectric properties of the CNT films were investigated in detail.The nanotubes doped using a cationic surfactant(cetyltrimethylammonium chloride(CTAC))retained an n-doped state for at least 28 days when exposed to water and air,indicating higher stability than that for contemporary CNT-based thermoelectric materials.The wrapping of the surfactant molecules around the CNTs is responsible for blocking oxygen and water from attacking the CNT walls,thus,extending the lifetime of the n-doped state of the CNTs.We also fabricated thermoelectric power conversion modules comprising CTAC-doped(n-type)and sodium dodecylbenzenesulfonate-(SDBS-)doped(p-type)CNTs and tested their stabilities in water.The modules retained 80±2:4%of their initial maximum output power(at a temperature difference of 75℃)after being submerged in water for 30 days,even without any sealing fills to prevent device degradation.The remarkable stability of our CNT-based modules can enable the development of reliable soft electronics for underwater applications.