PAF-1 as oxygen tank to in-situ synthesize edge-exposed O-MoS2 for highly efficient hydrogen evolution.

• We synthesized oxygen-incorporated MoS 2 ultrathin nanosheets by oxygen adsorbate. • The CPAF not only acts as a conductive template but also oxygen tank. • MoS 2 nanosheets expose more catalytically active edges grown on the CPAF surface. • The O-MoS 2 -CPAF catalyst exhibited a low onset potential of 0.088 V for HER. Developing highly-efficient and low-cost non-precious metal electrocatalysts toward the hydrogen evolution reaction (HER) is a promising strategy to solve the environmental pollution problems and energy demands. In this study, we synthesized oxygen-incorporated molybdenum disulfide (MoS 2) ultrathin nanosheets with expanded interlayer spacing (∼9.3 Å) induced by oxygen adsorbate, i.e., carbonized porous aromatic framework (CPAF), through a facile hydrothermal method. The CPAF not only acts as a conductive template but also oxygen tank , which enhances the transport of electrons of the MoS 2 -based electrocatalysts and provides oxygen for O-MoS 2 nanosheets. Owing to the high specific surface area, conductive template and oxygen source of CPAF, MoS 2 nanosheets can grow densely and uniformly on the CPAF surface, exposing catalytically active edges effectively. The O-MoS 2 -CPAF catalyst exhibited significantly improved catalytic activity toward hydrogen evolution reaction (HER) with a low onset potential of 0.088 V, a large current density (10.0 mA cm−2 at 0.17 V), a small Tafel slope of 44 mV per decade as well as excellent stability and device performance. [ABSTRACT FROM AUTHOR]