Introducing High-Valence Iridium Single Atoms into Bimetal Phosphides toward High-Efficiency Oxygen Evolution and Overall Water Splitting.

Single atoms are superior electrocatalysts having high atomic utilization and amazing activity for water oxidation and splitting. Herein, this work reports a thermal reduction method to introduce high-valence iridium (Ir) single atoms into bimetal phosphide (FeNiP) nanoparticles toward high-efficiency oxygen evolution reaction (OER) and overall water splitting. The presence of high-valence single Ir atoms (Ir4+ ) and their synergistic interaction with Ni3+ species as well as the disproportionation of Ni3+ assisted by Fe collectively contribute to the exceptional OER performance. In specific, at appropriate Ir/Ni and Fe/Ni ratios, the as-prepared Ir-doped FeNiP (Ir25 -Fe16 Ni100 P64 ) nanoparticles at a mass loading of only 35 µg cm-2 show the overpotential as low as 232 mV at 10 mA cm-2 and activity as high as 1.86 A mg-1 at 1.5 V versus RHE for OER in 1.0 m KOH. Computational simulations confirm the vital role of high-valence Ir to weaken the adsorption of OER intermediates, favorable for accelerating OER kinetics. Impressively, a Pt/C||Ir25 -Fe16 Ni100 P64 two-electrode alkaline electrolyzer affords a current density of 10 mA cm-2 at a low cell voltage of 1.42 V, along with satisfied stability. An AA battery with a nominal voltage of 1.5 V can drive overall water splitting with obvious bubbles released.

Synthesis of unconventional Pd-Se nanoparticles for phase-dependent ethanol electrooxidation.

By tuning the amount of the Se precursors during the synthesis, orthorhombic PdSe2, cubic Pd17Se15, and monoclinic Pd7Se2 nanoparticles are synthesized, which show phase-dependent electrocatalysis for the ethanol oxidation reaction. This work advances the controllable synthesis of transition metal selenides and inspires their applications in electrocatalysis.