Highly Sensitive Flexible Pressure Sensors based on Graphene/Graphene Scrolls Multilayer Hybrid Films

In recent years,flexible pressure sensors have attracted much attention owing to their potential applications in motion detection and wearable electronics.As a result,important innovations have been reported in both conductive materials and the underlying substrates,which are the two crucial components of a pressure sensor.1D materials like nanowires are being widely used as the conductive materials in flexible pressure sensors,but such sensors usually exhibit low performances mainly due to the lack of strong interfacial interactions between the substrates and 1D materials.In this paper,we report the use of graphene/graphene scrolls hybrid multilayers films as the conductive material and a microstructured polydimethylsiloxane substrate using Epipremnum aureum leaf as the template to fabricate highly sensitive pressure sensors.The 2D structure of graphene allows to strongly anchor the scrolls to ensure the improved adhesion between the highly conductive hybrid films and the patterned substrate.We attribute the increased sensitivity(3.5 k Pa^-1),fast response time(<50 ms),and the good reproducibility during 1000 loading-unloading cycles of the pressure sensor to the synergistic effect between the 1D scrolls and 2D graphene films.Test results demonstrate that these sensors are promising for electronic skins and motion detection applications.

A Layer-Structured Metal-Organic Framework-Derived Mesoporous Carbon for Efficient Oxygen Reduction Reaction

Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.

Ultrathin 2D Conjugated Polymer Nanosheets for Solar Fuel Generation

Two-dimensional(2 D) polymers are fascinating as they exhibit unique physical, chemical, mechanical, and electronic properties that are completely different from those of traditional linear or branched polymers. They are very promising for applications in catalysis, separation, optoelectronics, energy storage, and nanomedicine. Recently, ultrathin 2 D conjugated polymers have emerged as advanced materials for converting solar energy into chemical energy. The inherent 2 D planar structure with in-plane periodicity offers many features that are highly desirable for photon-involved catalytic energy conversion processes, including high absorption coefficients,large surface areas, abundant surface active sites, and efficient charge separation. Moreover, the possibility of finely tuning the optoelectronic and structural properties through precise molecular engineering has opened up new opportunities for design and synthesis of novel 2 D polymer nanosheets with unprecedented applications. Herein, we highlight recent advances in developing ultrathin 2 D conjugated polymer nanosheets for solar-to-chemical energy conversion. Specifically, we discuss emerging applications of ultrathin 2 D conjugated polymer nanosheets for solar-driven water splitting and CO2 reduction. Meanwhile, future challenges and prospects for design and synthesis of ultrathin 2 D conjugated polymer nanosheets for solar fuel generation are also included.