1D/2D Cobalt‐Based Nanohybrids as Electrocatalysts for Hydrogen Generation

Abstract The synergistic effects derived from optimizing the chemical and structural features of electrocatalysts permit them to attain remarkable activity and stability. Herein, 1D/2D cobalt‐based nanohybrid (CoNH) electrodes are developed; the structural design consists of Co 3 O 4 electrospun nanoribbons (NRs) deposited onto a carbon fiber paper substrate where Co 3 O 4 nanosheets are subsequently grown via an electrodeposition step and UV/ozone treatment. The content of noncovalently functionalized carbon nanotubes within the Co 3 O 4 NRs is first tuned to enhance their charge transfer properties and mechanical stability. The electrocatalytic activity of the electrodes is further improved by a phosphorus modification of the 1D NRs, resulting in the formation of NaCoPO 4 . The optimized 1D/2D CoNH electrode, i.e., ED‐0.09 wt% fCNTs/P‐CoNHs, displays a similar performance to that of platinum in 0.25 m Na 2 S/0.35 m Na 2 SO 3 (Tafel slope ≈102 mV dec −1 for the former and ≈96 mV dec −1 for the latter) and outstanding stability for up to 48 h. The versatility and high activity of this electrode is also demonstrated according to tests in a conventional water splitting system (cell voltage 1.55V, to produce 10 mA cm −2 ) and a solar‐driven electrolyzer (1 m KOH).