Real-Time Tunable Gas Sensing Platform Based on SnO_(2) Nanoparticles Activated by Blue Micro-Light-Emitting Diodes

Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power consumption.However,despite these benefits,challenges still exist such as a limited range of detectable gases and slow response.In this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power consumption.The optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain simulation.Additionally,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)NPs.The noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and C2H5OH.Real-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.

Vertically aligned one-dimensional ZnO/V2O5 core-shell hetero-nanostructure for photoelectrochemical water splitting

The vertically aligned one-dimensional(1 D)core-shell structure can maximize the exposure and use of the functionally active surface while maintaining the geometric effects caused by the underlying structure.Herein,we have fabricated 1 D vertically aligned ZnO/V2O5 core-shell hetero-nanostructure nanorod arrays(NRs)for photoelectrochemical(PEC)water splitting.ZnO/V2O5 NRs were prepared through the hydrothermal growing of ZnO NRs and then radio frequency(RF)magnetron sputtering deposition of V2O5 for 300,600 and 900 s.The photocurrent density of ZnO/V2O5-based photoanodes was gradually increased with the sputtering time,reaching the maximum value of 1.21 m A/cm^2 at 1.23 V vs.reversible hydrogen electrode(RHE)for ZnO/V2O5-600,whereas for pure ZnO-based photoanode was 0.42 mA/cm^2.The incident photon to electron conversion efficiency(IPCE)of ZnO/V2O5-600 evaluated to be 82.3%which was 2.3 times higher than that of ZnO(36.4%).The improved PEC performance of ZnO/V2O5-600 is because the core-shell structure with a moderate thickness of the V2O5 layer has the extremely high carrier density,largest electrochemically active surface area(ECSA),largest carrier density,lowest charge recombination rate,and the longest lifetime of e-h pairs due to the formation of the staggered gap junction.This study provides an effective way to design and fabrication of hetero-nanostructures for highefficiency photoelectrodes.

Toward stable photoelectrochemical water splitting using NiOOH coated hierarchical nitrogen-doped ZnO-Si nanowires photoanodes

Photoelectrochemical(PEC)water splitting is regarded as the most promising method to generate“green hydrogen”,and zinc oxide(ZnO)has been identified as one of the promising candidates for PEC water splitting owing to its straddling band alignment with the water redox level.However,its PEC performance is limited due to its wide bandgap and anticipated by photocorrosion in an aqueous medium.In this work,we present strategic improvements in the PEC water splitting performance of ZnO nanowires(NWs)by nitrogen(N)-doping along with photostability by the core–shell deposition of a NiOOH cocatalyst.Highly crystalline hierarchical ZnO NWs were fabricated on Si NWs(ZnO-Si HNWs)using a metal organic chemical vapor deposition approach.The NWs were then N-doped by annealing in an NH_(3) atmosphere.The N-doped ZnO-Si HNWs(N:ZnO-Si HNWs)showed enhanced visible light absorption,and suppressed recombination of the photogenerated carriers.As compared to ZnO-Si HNWs(0.045 m A cm^(-2) at 1.23 V vs RHE),the N:ZnO-Si HNWs(0.34 m A cm^(-2) at 1.23 V vs RHE)annealed in NH^(3) ambient for 3 h at 600℃showed 7.5-fold enhancement in the photocurrent density.NiOOH-deposited N:ZnO-Si HNW photoanodes with a photostability of 82.21%over 20000 s showed 10.69-fold higher photocurrent density(0.48 m A cm^(-2) at 1.23 V vs RHE)than ZnO-Si HNWs.

Self-powered and flexible piezo-sensors based on conductivitycontrolled GaN nanowire-arrays for mimicking rapid-and slow-adapting mechanoreceptors

Human skin contains slowly adaptive(SA)and rapidly adaptive(RA)mechanoreceptors,which respond differently to external stimuli.Based on human tactile perception principles,the fabrication of a self-powered electronic skin(e-skin)that simultaneously mimics SA-and RA-mechanoreceptors is a prime need for robots and artificial prosthetics to interact with the surrounding environment.However,the complex process of merging multimode sensors to mimic SA-and RA-mechanoreceptors hinders their utilization in e-skins.We proposed SA-and RA-mechanoreceptors based on n-type and semi-insulating GaN nanowire arrays.The SA-and RA-mechanoreceptors demonstrated distinguished features such as grasping of objects and detection of their surface textures.Based on piezoelectric sensing principles,the proposed e-skin can simultaneously mimic static and dynamic pressure signals.Mechanoreceptors further detected several stimuli of various pressures with low and high frequencies.The response and reset times showed by SA-mechanoreceptors were 11 and 18 ms under 1-Hz frequency,which are rapid enough for practical e-skin applications.