RESUMEN
Hierarchical porous iron and nitrogen co-doped carbon (Fe-N/C) materials have been considered as an appealing non-noble metal-based catalyst in oxygen reduction reactions (ORR). However, the conductivity loss caused by the scattering of electrons on pores and defects markedly limits their catalytic activity, which attracted seldom attention in this area. Herein, a novel crystalline carbon modified hierarchical porous Fe-N/C electrocatalyst with enhanced electronic conductivity is designed and prepared via a two-step calcination-catalysis process. The resistivity of hierarchical porous Fe-N/C is decreased from 2.123 Ω cm to 0.479 Ω cm after crystalline carbon introduction. The electrocatalyst annealed at 800 °C (Fe-N/C-800) exhibits a superior activity with the half-wave potential (E1/2) of 0.89 V, which outperforms the commercial carbon-supported platinum (Pt/C) catalyst (0.85 V). The strategy of crystalline carbon modification provides a fresh approach to improve the electronic conductivity of porous carbon-based materials.
RESUMEN
Photocatalytic stability and efficient charge separation are key factors to photocatalytic performance for visible-light-driven H2 evolution from water. Here, we report a whole novel self-rectified photocatalyst constructed from the Shockley partial dislocation-induced multiple faults, using a ternary chalcogenide, that is, Cd0.8Zn0.2S nanorod as a model material. The introduction of multiple faults, which are typical planar defects, constructs a nanorectifier that aligns along the axial direction and constitutes a relatively ordered superstructure. The band bending and Fermi-level flattening at the nanorectifier would cause the photogenerated charge carriers to be transferred reversely at the axial direction on account of the charge type and then realize the separation of the charge carriers.