Lin Zeng

A high-performance supportless silver nanowire catalyst for anion exchange membrane fuel cells

Silver has been widely investigated as a cathode catalyst owing to its stable and high electrocatalytic activity in anion exchange membrane fuel cells (AEMFCs). In this work, we synthesize silver nanowires (Ag NWs) using the polyol synthesis method and demonstrate that the supportless Ag NWs exhibit an extraordinarily high electrocatalytic activity toward the oxygen reduction reaction in a three-electrode cell. More significantly, the use of supportless Ag NWs as the cathode catalyst in a H2/O2 AEMFC yields a peak power density of 164 mW cm−2 at 60 °C, which is favorably comparable to the state-of-the-art AEMFCs with carbon-supported Ag catalysts. In addition to the increased electrocatalytic activity, the improved performance is attributed to the elongated wire morphology of Ag NWs which allows a well-established porous electrode structure to form in the cathode. The high-performance supportless Ag NWs offer a promising alternative to carbon-supported electrocatalysts in fuel cells and metal–air batteries, to eliminate the carbon supporting materials.

Highly efficient and ultra-stable boron-doped graphite felt electrodes for vanadium redox flow batteries

Developing high-performance electrodes with high operating current densities and long-term cycling stability is crucial to the widespread application of vanadium redox flow batteries (VRFBs). In this work, boron-doped graphite felt electrodes are designed, fabricated and tested for VRFBs. The first-principles study first demonstrates that the boron-doped carbon surface possesses highly active and stabilized reaction sites. Based on this finding, boron-doped graphite felt electrodes are fabricated for VRFBs. Testing results show that the batteries with boron-doped graphite felt electrodes achieve energy efficiencies of 87.40% and 82.52% at the current densities of 160 and 240 mA cm−2, which are 15.63% and 19.50% higher than those with the original electrodes. In addition, the batteries can also be operated at high current densities of 320 and 400 mA cm−2 with energy efficiencies of 77.97% and 73.63%, which are among the highest performances in the open literature. More excitingly, the VRFBs with the boron-doped graphite felt electrodes exhibit excellent stability during long-term cycling tests. The batteries can be stably cycled for more than 2000 cycles at 240 mA cm−2 with ultra-low capacity and efficiency decay rates of only 0.028% and 0.0002% per cycle. In addition, after refreshing the electrolytes, the performances of the batteries are nearly recovered regardless of the inevitable decay of the membrane. All these results suggest that highly efficient and ultra-stable boron-doped graphite felts are promising electrodes for VRFBs.