Phytic acid empowered two nanos ?Polypyrrole tunnels and transition Metal-(Oxy)hydroxide Sheets? in a single platform for unmitigated redox water splitting

Transition metal oxyhydroxide electrocatalysts, which have immense potential of overall water splitting, help to relieve energy scarcity. Herein, we describe a novel perspective for designing transition metal oxyhydroxide bifunctional electrocatalysts by fabricating green and renewable biological phytic acid-incorporated polypyrrole nanotunnels with luminal-abluminal NiCo-(oxy)hydroxide nanosheets fastened on both sides of a carbon cloth (NiCo-OHO@PA-PPy-NTs@CC (1:1)). Polypyrrole tunnels with delocalizing pi-electrons contribute not only as a high mass loading facility but also leverage the rapid electron/charge transportation, sidestepping the fast phase changes of metallic oxyhydroxide during the electrolysis of water. Six phosphate groups of phytic acid cross-link the metal ions, confining their migration and aggregation, leading to the homogeneous dispersion of metal ions which provides more active sites for the evolution of H2 and O2. Additionally, phytic acid-incorporated PPy networks enhance the hydrophilicity of the surface, boosting effective contact between the catalyst and elec-trolytes, which escalates to excellent electrode kinetics for the HER and OER. The bifunctional electrocatalyst required an ultralow cell voltage of 1.51 V to achieve a current density of 10 mA cm-2 with 100% Faradaic efficiency, signifying its potential for practical overall water splitting as a replacement for noble metal catalysts.