No abstract

Capacitance loss with the increase of mass loading represents an outstanding challenge for supercapacitors. Here we demonstrate for the first time a mm-thick, 3D printed graphene aerogel structure that can support pseudocapacitive MnO 2 to hundreds of mg/cm 2 without sacrificing its gravimetric and volumetric performance. The electrode simultaneously achieves high gravimetric, areal, and volumetric capacitances, which is impossible for conventional bulk electrodes. Most importantly, these findings validate the new concept of ''printing'' practically feasible pseudocapacitor electrodes and devices.

Replacing liquid electrolytes with a versatile, solid-state membrane based on highly functionalized cellulose nanofibers allows for easy integration of rechargeable zinc–air into any bendable and wearable devices.

Despite the good progress in developing doped carbon catalysts for oxygen-reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing new metal free doped carbon materials with abundance active sites as well as excellent electron transfer and reactant transport rate towards ORR may be a potential solution. Herein, we develop a novel three-dimensional (3D) sulfur-nitrogen co-doped carbon foams (S-N-CF) with hierarchical pore structures, using a convenient, economical, and scalable method. The experimental results have demonstrated that the obtained 3D S-N-CF exhibited better catalytic activity, longer-term stability and higher methanol tolerance than a commercial Pt/C catalyst. Such excellent performances may be attributed to the synergistic effect, which includes high catalytic sites for ORR provided by high S-N heteroatom loading, excellent reactant transport caused by hierarchical pore structures and high electron transfer rate provided by 3D continuous networks. Our results not only develop a new type of catalysts with excellent electrocatalytic performance by a commercially valid route, but also provide useful information for further clarification of the relationship between the microstructures of metal-free carbon materials and catalyst properties for ORR. More importantly, the idea to design hierarchical pore structures could be applied to other catalytic materials and serve as a general strategy for improving the activity of various ORR catalysts.