Nanoparticle-Decorated Ultrathin La2O3 Nanosheets as an Effcient Electrocatalysis for Oxygen Evolution Reactions

Electrochemical catalysts for oxygen evolution reaction are a critical component for many renewable energy applications. To improve their catalytic kinetics and mass activity are essential for sustainable industrial applications. Here, we report a rare-earth metal-based oxide electrocatalyst comprised of ultrathin amorphous La2O3 nanosheets hybridized with uniform La2O3 nanoparticles(La2O3@NP-NS). Significantly improved OER performance is observed from the nanosheets with a nanometer-scale thickness. The as-synthesized 2.27-nm La2O3@NP-NS exhibits excellent catalytic kinetics with an overpotential of 310 mV at 10 m A cm^-2, a small Tafel slope of 43.1 mV dec^-1, and electrochemical impedance of 38 Ω. More importantly, due to the ultrasmall thickness, its mass activity, and turnover frequency reach as high as 6666.7 A g^-1 and 5.79 s^-1, respectively, at an overpotential of 310 mV. Such a high mass activity is more than three orders of magnitude higher than benchmark OER electrocatalysts, such as IrO2 and RuO2. This work presents a sustainable approach toward the development of highly e cient electrocatalysts with largely reduced mass loading of precious elements.

Stretchable on-skin touchless screen sensor enabled by ionic hydrogel

Screen sensors are the most commonly used human-machine interfaces in our everyday life,which have been extensively applied in personal electronics like cellphones.Touchless screen sensors are attracting growing interest due to their distinct advantages of high interaction freedom,comfortability,and hand hygiene.However,the material compositions of current touchless screen sensors are rigid and fragile,hardly meeting the needs of wearable and stretchable on-skin electronics development.Additionally,these touchless screen sensors are also restricted by high power consumption,limited gesture types of recognition,and the requirement of light conditions.Here,we report a stretchable on-skin touchless screen sensor(OTSS)enabled by an ionic hydrogel-based triboelectric nanogenerator(TENG).Compared with current touchless screen sensors,the OTSS is stretchable,self-powered,and competent to recognize diverse gestures by making use of charges naturally carried on fingers without the need of sufficient light conditions.An on-skin noncontact screen operating system is further demonstrated on the basis of the OTSS,which could unlock a cellphone interface in touchless operation mode on the human skin.This work for the first time introduces the on-skin touchless concept to screen sensors and offers a direction to develop new-generation screen sensors for future cellphones and personal electronics.

Intrinsically stretchable polymer semiconductor based electronic skin for multiple perceptions of force,temperature,and visible light

As a stretchable seamless device,electronic skin(E-skin)has drawn enormous interest due to its skin-like sensing capability.Besides the basic perception of force and temperature,multiple perception that is beyond existing functions of human skin is becoming an important direction for E-skin developments.However,the present E-skins for multiple perceptions mainly rely on different sensing materials and heterogeneous integration,resulting in a complex device structure.Additionally,their stretchability is usually achieved by the complicated microstructure design of rigid materials.Here,we report an intrinsically stretchable polymer semiconductor based E-skin with a simple structure for multiple perceptions of force,temperature,and visible light.The E-skin is on the basis of poly(3-hexylthiophene)(P3HT)nanofibers percolated polydimethylsiloxane(PDMS)composite polymer semiconductor,which is fabricated by a facile solution method.The E-skin shows reliable sensing capabilities when it is used to perceive strain,pressure,temperature,and visible light.Based on the E-skin,an intelligent robotic hand sensing and controlling system is further demonstrated.Compared with conventional E-skins for multiple perceptions,this E-skin only has a simple monolayer sensing membrane without the need of combining different sensing materials,heterogeneous integration,and complicated microstructure design.Such a strategy of utilizing intrinsically stretchable polymer semiconductor to create simple structured E-skin for multiple perceptions will promote the development of E-skins in a broad application scenario,such as artificial robotic skins,virtual reality,intelligent gloves,and biointegrated electronics.

Non-contact cylindrical rotating triboelectric nanogenerator for harvesting kinetic energy from hydraulics

Hydraulics provide a unique and widely existed mechanical energy source around us,such as in water or oil pipes,and sewers.Here,a non-contact cylindrical rotating triboelectric nanogenerator(TENG)was developed to harvest the mechanical energy from water flows.Operation of the TENG was based on the non-contact free-rotating between a curved Cu foil and a flexible nanostructured fluorinated ethylene propylene(FEP)polymer film.The free-standing distance between two rotating interfaces avoided abrading of electrode materials.The TENG was able to effectively convert mechanical energy of the water flow into electricity.When driven by water flow,the output voltage and current of the TENG reached 1,670 V and 13.4 uA,respectively.Without any energy storage component,the produced electricity could instantaneously power 12 white light emitting diodes(LEDs)bulbs and a digital timer.This non-contact rotating TENG would provide new opportunities for harvesting energy from many types of hydraulics as a self-sustainable power source for sensing,detection,and protection.

3D printed triboelectric nanogenerator as self-powered human–machine interactive sensor for breathing-based language expression

Human–machine interfaces(HMIs)are important windows for a human to communicate with the outside world.The current HMI devices such as cellphones,tablets,and computers can be used to help people with aphasia for language expression.However,these conventional HMI devices are not friendly to some particular groups who also lose their abilities of physical movements like in the intensive care unit(ICU)or vegetative patients to realize language expression.Herein,we report a breath-driven triboelectric nanogenerator(TENG)acting as a HMI sensor for language expression through human breathing without voice controls or manual operations.The TENG is integrated within a mask and fabricated via a three-dimensional(3D)printing method.When wearing the mask,the TENG can produce responsive electric signals corresponding to the airflow from breathing,which is capable of recognizing human breathing types with different intensities,lengths,and frequencies.On the basis of the breathing recognition ability,a breathing-based language expressing system is further developed through introducing the Morse code as a communication protocol.Compared with conventional language expressing devices,this system can extract subjective information of a person from breathing behaviors and output corresponding language text,which is not relying on voices or physical movements.This research for the first time introduces the self-powered breathing-based language expressing method to the field of HMI technology by using a 3D printed TENG,and could make HMI interactions become more friendly and fascinating.