Metal-Organic Framework-Derived Three-Dimensional Macropore Nitrogen-Doped Carbon Frameworks Decorated with Ultrafine Ru-Based Nanoparticles for Overall Water Splitting.

Hydrogen energy with the advantages of green, sustainability, and high energy density has been considered as an alternative to fossil fuel energy. Water electrolysis to produce hydrogen is a promising energy conversion technology but limited to the large overpotential; thus, a highly efficient electrocatalyst is urgently needed. Herein, Ru-based electrocatalysts including an ultrathin Ru/three-dimensional (3D) macropore N-doped carbon framework (Ru/3DMNC) and ultrathin RuO2/3D macropore N-doped carbon framework (RuO2/3DMNC) are first prepared using a Zn-centered metal-organic framework (MOF, ZIF-8) as the precursor. The ultrathin 3D macropore framework structure together with N doping endows the as-synthesized Ru-based electrocatalysts with abundant exposed catalytic active sites, good electroconductivity, and excellent electron/mass transport, accomplishing improved activities for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The Ru/3DMNC and RuO2/3DMNC present low overpotentials of 50.96 and 216.74 mV to reach a current density of 10 mA cm-2. Moreover, the overall water splitting device constructed by Ru/3DMNC and RuO2/3DMNC as the cathode and anode catalysts, respectively, affords a current density of 10 mA cm-2 only at 1.51 V, which is superior to the Pt/C||RuO2 cell (1.573 V). This work provides a rational strategy to design and construct the efficient framework structure electrocatalysts for water splitting using MOFs as the precursor.