Carbon dots regulate the interface electron transfer and catalytic kinetics of Pt-based alloys catalyst for highly efficient hydrogen oxidation

The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.

The advanced multi-functional carbon dots in photoelectrochemistry based energy conversion

Carbon dots(CDs),as a unique zero-dimensional member of carbon materials,have attracted numerous attentions for their potential applications in optoelectronic,biological,and energy related fields.Recently,CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization,fast migration of charge carriers,efficient surface redox reactions and good electrical conductivity.In this review,we summarize the fabrication methods of CDs and corresponding CD nanocomposites,including the strategies of surface modification and heteroatom doping.The properties of CDs that concerned to the photo-and electro-catalysis are highlighted and detailed corresponding applications are listed.More importantly,as new non-contact detection technologies,transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics,which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts.The development and application of the techniques are reviewed.Finally,we discuss and outline the major challenges and opportunities for future CD-based catalysts,and the needs and expectations for the development of novel characterization technologies.

Extremely stable Li-metal battery enabled by piezoelectric polyacrylonitrile quasi-solid-state electrolytes

Polymer solid-state electrolytes(PSSEs)are promising for solving the safety problem of Lithium(Li)metal batteries(LMBs).However,PSSEs with low modulus in nature are prone to be penetrated by lithium dendrites,resulting in short circuit of LMBs.Here,we design and prepare piezoelectric BaTiO_(3)doped polyacrylonitrile(PAN@BTO)quasi-solid-state electrolytes(PQSSEs)by electrostatic spinning method to suppress dendritic growth.The piezoelectric polymer electrolytes are squeezed by nucleation and growth processes of Li dendrites,which can generate a piezoelectric electric field to regulate the deposition of Li^(+)ions and eliminate lithium bud.Consequently,piezoelectric PAN@BTO PQSSEs enables highly stable Li plating/stripping cycling for over 2000 h at 0.15 mA/cm^(2)at room temperature(RT,25℃).Also,LiFePO_(4)|PAN@BTO|Li full cells demonstrate excellent cycle performance(136.9 mA·h/g and 78%retention after 600 cycles at 0.5 C)at RT.Moreover,LiFePO_(4)|PAN@BTO|Li battery show extremely high safety and can still work normally under high-speed impact(2 Hz,∼30 kPa).We construct an in-situ cell monitoring system and disclose that the mechanism of suppressed lithium dendrite is originated from the generation of opposite piezoelectric potential and the feedback speed of intermittent piezoelectric potential signals is extremely fast.

Exploration of interconnected factory mode: Haier Jiaozhou Air Conditioner Interconnected Factory

Haier Jiaozhou Air Conditioner Interconnected Factory('Haier Interconnected Factory'for short hereinafter)was constructed by Haier Group in Haier(Jiaozhou)Innovative Industrial Park with a total investment of 1 billion CNY and a registered capital of 100 million CNY.The factory covers an area of 140 mu or approximately 100,000 m^2.It is the largest individual building for producing

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.

Carbon dots modified Ti_(3)C_(2)T_(x)-based fibrous supercapacitor with photo-enhanced capacitance

The energy crisis has always been a widely concerned problem. It is an urgent need for green and renewable energy technologies to achieve sustainable development, and the photo-assisted charging energy storage devices provide a new way to realize the sustainable utilization of solar energy. Here, we fabricated a photo-assisted charging fibrous supercapacitor (NM2P1) with Ti_(3)C_(2)T_(x)-based hybrid fibre modified by nitrogen-doped carbon dots (NCDs). The NM2P1 fibre provides a volumetric capacitance of 1,445 F·cm^(−3) (630 F·g^(−1)) at 10 A·cm^(−3) under photo-assisted charging, which increases by 35.9% than that of dark condition (1,063 F·cm^(−3)/464 F·g^(−1)). Furthermore, the NM2P1 fibrous supercapacitor device shows that the maximum volumetric energy density and volumetric power density are 18.75 mWh·cm^(−3) and 8,382 mW·cm^(−3). Notably, the transient photovoltage (TPV) test was used to further confirm that NCDs as a photosensitizer enhance the light absorption capacity and faster charge transfer kinetics of NM2P1 fibre. This work directly exploits solar energy to improve the overall performance of supercapacitor, which opens up opportunities for the utilization of renewable energy and the development of photosensitive energy equipment.

Continuously Quantifying Oral Chemicals Based on Flexible Hybrid Electronics for Clinical Diagnosis and Pathogenetic Study

Simultaneous monitoring of diverse salivary parameters can reveal underlying mechanisms of intraoral biological processes and offer profound insights into the evolution of oral diseases.However,conventional analytical devices with bulky volumes,rigid formats,and discrete sensing mechanisms deviate from the requirements of continuous biophysiological quantification,resulting in huge difficulty in precise clinical diagnosis and pathogenetic study.Here,we present a flexible hybrid electronic system integrated with functional nanomaterials to continuously sense Ca^(2+),pH,and temperature for wireless real-time oral health monitoring.The miniaturized system with an island-bridge structure that is designed specifically to fit the teeth is only 0.4g in weight and 31.5×8.5×1.35 mm^(3) in dimension,allowing effective integration with customized dental braces and comfort attachment on teeth.Characterization results indicate high sensitivities of 30.3 and 60.6 mV/decade for Ca^(2+)and pH with low potential drifts.The system has been applied in clinical studies to conduct Ca^(2+)and pH mappings on carious teeth,biophysiological monitoring for up to 12 h,and outcome evaluation of dental restoration,providing quantitative data to assist in the diagnosis and understanding of oral diseases.Notably,caries risk assessment of 1o human subjects using the flexible system validates the important role of saliva buffering capacity in caries pathogenesis.The proposed flexible system may offer an open platform to carry diverse components to support both clinical diagnosis and treatment as well as fundamental researchfororaldiseases and induced systemicdiseases.