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

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).