Biomimetic design of ultrathin edge-riched FeOOH@Carbon nanotubes as high-efficiency electrocatalysts for water splitting.

Biomimetic design is achieved to synthesize FeOOH@CNTs composite with ultrathin edge-riched FeOOH "leaves" supported by CNT "branches" as OER catalyst. The "leaf-branch" structural FeOOH@CNTs catalyst exhibits superior catalytic activity to commercial RuO 2. • Biomimetic design of FeOOH@CNTs with ultrathin FeOOH "leaves" on carbon nanotube "branches". • The "leaf-branch" structural FeOOH@@CNTs exposes much more catalytic active sites for OER. • The synergistic effect of FeOOH "leaves" and CNT "branches" reduced the energy barrier for OER. • The FeOOH@@CNTs exhibits yet the best catalytic performances for overall water splitting. Based on a plant-like morphology, here, we report a multidimensional composite with ultrathin edge-riched FeOOH "leaves" growing on carbon nanotube "branches" (FeOOH@CNTs) via a facile and environmentally benign approach. A Fenton reaction was adopted to oxidize carbon nanotubes (CNTs), and FeOOH flakes were generated on the CNTs as reaction proceeded. The highly conductive CNT "branches" ensure rapid electron transmission and compensate for low conductivity of the FeOOH "leaves". Meanwhile, ultrathin FeOOH "leaves" growing on CNT "branches" expose sufficient numbers of active sites for oxygen evolution reaction (OER). Density functional theory (DFT) computational results indicate that FeOOH@CNTs exhibit better OER catalytic performance than FeOOH. To achieve water splitting, FeOOH@CNTs were deposited on nickel foam as an anode, with platinum (Pt) sheet used as a cathode. A low cell voltage of only 1.44 V was achieved to yield a current density of 10 mA cm–2 with a TOF of 12.50 s-1. [ABSTRACT FROM AUTHOR]