Designing and synthesizing a highly active single atom catalyst, especially monodispersed noble-metal atoms fixed in two-dimensional layered double hydroxide (LDH) nanostructures, is crucial in accelerating the slow oxygen evolution reaction (OER). Here, Ru single atoms (SAs) are stabilized on NiFe LDH (SARu/NiFe LDH) via an oxygen-coordinated bond after a facile solution reduction procedure. The OER activity evaluation at similar mass loading on glassy carbon reveals that SARu/NiFe LDH shows more activity than pure NiFe LDH in basic media, possessing 99.3% of Faradaic efficiency based on rotating ring-disk electrode measurement. This is mainly due to a strong synergy between Ru SAs and NiFe LDH support. Furthermore, these supported catalysts are developed to an integrative 3D electrode in situ of the nickel foam with a higher specific surface area, which needs only an ultralow overpotential of 196 mV at 10 mA cm–2. This is one of the most efficient electrode containing monoatomic components to date. Theoretical calculations suggests that active sites of Ru can facilitate the rearrangement of electrons and optimize the binding energy both SARu/NiFe LDH catalyst and intermediates during the OER, thereby improving the intrinsic OER activity. This study provides a general avenue to developing efficiently monoatomic and even multiatomic catalysts in the future.

Developing non-noble metal-based core–shell heterojunction electrocatalysts with high catalytic activity and long-lasting stability is crucial for the oxygen evolution reaction (OER). Here, we prepared novel core–shell Fe,V-NiSe2@NiFe­(OH)x heterostructured nanoparticles on hydrophilic-treated carbon paper with high electronic transport and large surface area for accelerating the oxygen evolution rate via high-temperature selenization and electrochemical anodic oxidation procedures. Performance testing shows that Fe,V-NiSe2@NiFe­(OH) x possesses the highest performance for OER compared to as-prepared diselenide core-derived heterojunctions, which only require an overpotential of 243 mV at 10 mA cm–2 and a low Tafel slope of 91.6 mV decade–1 under basic conditions. Furthermore, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) confirm the morphology and elementary stabilities of Fe,V-NiSe2@NiFe­(OH) x after long-term chronopotentiometric testing. These advantages are largely because of the strong synergistic effect between the Fe,V-NiSe2 core with high conductivity and the amorphous NiFe­(OH) x shell with enriched defects and vacancies. This study also presents a general approach to designing and synthesizing more active core–shell heterojunction electrocatalysts for OER.