Pushing the Electrochemical Performance Limits of Polypyrrole Toward Stable Microelectronic Devices

Conducting polymers have achieved remarkable attentions owing to their exclusive characteristics,for instance,electrical conductivity,high ionic conductivity,visual transparency,and mechanical tractability.Surface and nanostructure engineering of conjugated conducting polymers offers an exceptional pathway to facilitate their implementation in a variety of scientific claims,comprising energy storage and production devices,flexible and wearable optoelectronic devices.A two-step tactic to assemble high-performance polypyrrole(PPy)-based microsupercapacitor(MSC)is utilized by transforming the current collectors to suppress structural pulverization and increase the adhesion of PPy,and then electrochemical co-deposition of PPy-CNT nanostructures on rGO@Au current collectors is performed.The resulting fine patterned MSC conveyed a high areal capacitance of 65.9 mF cm^(−2)(at a current density of 0.1 mA cm^(−2)),an exceptional cycling performance of retaining 79%capacitance after 10,000 charge/discharge cycles at 5 mA cm^(−2).Benefiting from the intermediate graphene,current collector free PPy-CNT@rGO flexible MSC is produced by a facile transfer method on a flexible substrate,which delivered an areal capacitance of 70.25 mF cm^(−2) at 0.1 mA cm^(−2) and retained 46%of the initial capacitance at a current density of 1.0 mA cm^(−2).The flexible MSC is utilized as a skin compatible capacitive micro-strain sensor with excellent electromechanochemical characteristics.

Platinum nickel alloy-MXene catalyst with inverse opal structure for enhanced hydrogen evolution in both acidic and alkaline solutions

The development of an efficient Pt-based electrocatalyst in acidic and alkaline electrolytes is of great significance to the field of electrocatalytic hydrogen evolution.Herein,we report a strategy for in situ growth of Pt_(3)Ni truncated octahedrons on Ti3C2Tx nanosheets and then obtain an ordered porous catalyst via a template method.Meanwhile,we use the finite element calculation to clarify the relationship between the component structure and performance and find that the performance of the spherical shell microstructure catalyst is higher than that of the disc structure catalyst,which is also verified by experiments.The experimental analysis shows that the ordered porous catalyst is conducive to enhancing electrocatalytic hydrogen evolution activity in acidic and alkaline electrolytes.In an acidic solution,the overpotential is 25 mV(10 mA·cm^(−2)),and the Tafel slope is 22.86 mV·dec−1.In an alkaline solution,the overpotential is 44.1 mV(10 mA·cm^(−2)),and the Tafel slope is 39.06 mV·dec−1.The synergistic coupling between Ti3C2Tx and Pt_(3)Ni nanoparticles improves the stability of the catalyst.The in situ growth strategy and design of microstructure with its correlation with catalytic performance represent critical steps toward the rational synthesis of catalysts with excellent catalytic activity.

Examination on the wear process of polyformaldehyde gears under dry and lubricated conditions

This study presents the results of detailed wear process examination on polyformaldehyde gears under both dry and lubricated conditions.A multi-purpose durability test rig was employed to study the wear performance of polyformaldehyde gear pairs.The wear behaviors of polyformaldehyde gears under dry and oil-lubricated operating conditions were characterized via measurements of gear tooth surface micro-topography and tooth profile deviation.Under the dry running condition,a hump and a gully appear on the tooth surface in the pitch line area of the driving gear and the driven wheel,respectively.The largest amount of wear was observed around the tooth root of the driving gear.However,the gear tooth wear pattern with lubrication is different from that under the dry running condition.