In situ constructing of ultrastable ceramic@graphene core-shell architectures as advanced metal catalyst supports toward oxygen reduction

The changeable structure of 2 D graphene nanosheets makes the Pt-based nanoparticles（NPs） possess a low efficiency toward oxygen reduction reaction（ORR） and a short lifetime for proton exchange membrane fuel cells. Thus, a unique Ti C@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs.The as-prepared Pt/GNS@Ti C catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2 D graphene nanosheets,impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 m V cmunder a low Pt loading(0.25 mg Pt cm) and H/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields.

Flexible wide-range multidimensional force sensors inspired by bones embedded in muscle

Flexible sensors have been widely studied for use in motion monitoring,human‒machine interactions(HMIs),personalized medicine,and soft intelligent robots.However,their practical application is limited by their low output performance,narrow measuring range,and unidirectional force detection.Here,to achieve flexibility and high performance simultaneously,we developed a flexible wide-range multidimensional force sensor(FWMFS)similar to bones embedded in muscle structures.The adjustable magnetic field endows the FWMFS with multidimensional perception for detecting forces in different directions.The multilayer stacked coils significantly improved the output from theμV to the mV level while ensuring FWMFS miniaturization.The optimized FWMFS exhibited a high voltage sensitivity of 0.227 mV/N(0.5–8.4 N)and 0.047 mV/N(8.4–60 N)in response to normal forces ranging from 0.5 N to 60 N and could detect lateral forces ranging from 0.2–1.1 N and voltage sensitivities of 1.039 mV/N(0.2–0.5 N)and 0.194 mV/N(0.5–1.1 N).In terms of normal force measurements,the FWMFS can monitor finger pressure and sliding trajectories in response to finger taps,as well as measure plantar pressure for assessing human movement.The plantar pressure signals of five human movements collected by the FWMFS were analyzed using the k-nearest neighbors classification algorithm,which achieved a recognition accuracy of 92%.Additionally,an artificial intelligence biometric authentication system is being developed that classifies and recognizes user passwords.Based on the lateral force measurement ability of the FWMFS,the direction of ball movement can be distinguished,and communication systems such as Morse Code can be expanded.This research has significant potential in intelligent sensing and personalized spatial recognition.