Bottom-up Preparation of Hierarchically Porous MOF-modified Carbon Spheres Derivatives for Efficient Oxygen Reduction
The rational design and controllable preparation of carbon-based catalysts for oxygen reduction reactions (ORR) are at the core of key technologies for fuel cells and chargeable batteries in advanced energy conversion and storage. In the present work, the Co species by tuning the Zn dopant content in the precursors of bimetallic zeolitic-imidazolate framework functionalized carbon spheres (CoZn-ZIF/CS), generating the formation Co nanoparticles on N-doped carbon spheres at 1000 oC (CoZn-ZIF/CS-1000), are bottom-up synthesized and extensively investigated for the ORR performance. For the CoZn-ZIF/CS-1000, its Brunauer-Emmett-Teller surface area and total pore volume are well preserved from porous ZIF precursor up to 586 m2 g-1 and 0.39 cm3 g-1, respectively. As expected, it exhibits high-activity ORR performance in alkaline medium with a half-wave potential of 0.82 V vs. RHE and the diffusion limited current density of 5.11 mV cm-2. Meanwhile, the obtained CoZn-ZIF/CS-1000 electrocatalyst shows better electrochemical stability and methanol tolerance than the commercial Pt/C. Therefore, our discovery opens up a new way to regulate the catalytic performance of carbon material templates and MOF derivatives, which could be further applied in developing highly active catalysts in chemical energy utilization.