Synthesis of phosphonated graphene oxide by electrochemical exfoliation to enhance the performance and durability of high-temperature proton exchange membrane fuel cells

The doping of functionalized graphene oxide(GO)in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFC).Phosphonated graphene oxide(PGO)with a P/O ratio of 8.5%was quickly synthesised by one-step electrochemical exfoliation based on a three-dimensiaonal(3D)printed reactor and natural graphite flakes.Compared with the GO prepared by the two-step electrochemical exfoliation method,the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly(MEA)based on the polybenzimidazole(PBI)membrane in the HTPEMFC.The doping of 1.5 wt%GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4%or 35.4%compared to MEA based on pure PBI membrane at 150℃,respectively.In addition,the doping of PGO in PBI improves its durability under accelerated stress test(AST).

Zero-waste emission design of sustainable and programmable actuators

Moisture-responsive actuators are widely used as energy-harvesting devices due to their excellent ability to spontaneously and continuously convert external energy into kinetic energy.However,it remains a challenge to sustainably synthesize moisture-driven actuators.Here,we present a sustainable zero-waste emission methodology to prepare soft actuators using carbon nano-powders and biodegradable polymers through a water evaporation method.Due to the water solubility and recyclability of the matrixes employed here,the entire synthetic process achieves zero-waste emission.Our composite films featured strong figures of merit and capabilities with a 250◦maximum bending angle under 90%relative humidity.Programmable motions and intelligent bionic applications,including walkers,smart switches,robotic arms,flexible excavators,and hand-shaped actuators,were further achieved by modulating the geometry of the actuators.This sustainable method for actuators’fabrication has great potential in large-scale productions and applications due to its advantages of zero-waste emission manufacturing,excellent recyclability,inherent adaptive integration,and low cost.