Hollow TiO(2)@Co(9)S(8) Core–Branch Arrays as Bifunctional Electrocatalysts for Efficient Oxygen/Hydrogen Production

Designing ever more efficient and cost‐effective bifunctional electrocatalysts for oxygen/hydrogen evolution reactions (OER/HER) is greatly vital and challenging. Here, a new type of binder‐free hollow TiO(2)@Co(9)S(8) core–branch arrays is developed as highly active OER and HER electrocatalysts for stable overall water splitting. Hollow core–branch arrays of TiO(2)@Co(9)S(8) are readily realized by the rational combination of crosslinked Co(9)S(8) nanoflakes on TiO(2) core via a facile and powerful sulfurization strategy. Arising from larger active surface area, richer/shorter transfer channels for ions/electrons, and reinforced structural stability, the as‐obtained TiO(2)@Co(9)S(8) core–branch arrays show noticeable exceptional electrocatalytic performance, with low overpotentials of 240 and 139 mV at 10 mA cm(−2) as well as low Tafel slopes of 55 and 65 mV Dec(−1) for OER and HER in alkaline medium, respectively. Impressively, the electrolysis cell based on the TiO(2)@Co(9)S(8) arrays as both cathode and anode exhibits a remarkably low water splitting voltage of 1.56 V at 10 mA cm(−2) and long‐term durability with no decay after 10 d. The versatile fabrication protocol and smart branch‐core design provide a new way to construct other advanced metal sulfides for energy conversion and storage.