SAPO-34 templated growth of hierarchical porous graphene cages as electrocatalysts for both oxygen reduction and evolution

Three-dimensional hierarchical porous graphene materials with unique properties are of significant importance for the exploration of advanced electrocatalysts for both the oxygen reduction and evolution reactions (ORR/OER). Templated chemical vapor deposition is a favorable strategy to fabricate this kind of graphene, but the number of effective templates is limited. Here, silicoaluminophosphate (SAPO-34) zeolite crystals were used as the catalytic templates for the deposition of hierarchical porous graphene. The graphene obtained consisted of micron-size hollow cubes with mesoporous/nanoporous facets, and ultrathin walls, precisely replicating the structure of the cube-like SAPO-34 zeolite particles. A high doping level of nitrogen (6.84 at%) was achieved by subsequent annealing at 700 °C under ammonia before template removal. Because of the unique porosity, abundant defects, and favorable N-doping, the N-doped graphene exhibited considerable reactivity for both ORR and OER.