Hollow and Porous Nickel Cobalt Perselenide Nanostructured Microparticles for Enhanced Electrocatalytic Oxygen Evolution

Nickel and cobalt-based chalcogenides are an interesting class of electrochemically active compounds. Herein we report a two-step synthesis of uniform hollow nickel cobalt perselenide nanostructured microparticles with a corrugated surface, randomly spaced pores, and a tunable composition. In the first step, we synthesized Ni-Co acetate hydroxide prism shaped microparticles, which were subsequently used as templates for the selenization process at temperatures as low as 80 degrees C. The substitution of acetate and hydroxide anions with selenide anions at a low temperature eventually produced partially amorphous hollow microparticles due to the nanoscale Kirkendall effect. Thin films of the as-synthesized samples behaved as highly active catalysts for the electrochemical oxygen evolution reaction (OER). Among those, Ni0.88Co1.22Se4 hollow microparticles showed excellent performances, exhibiting a 10 mA/cm(2) current density at a modest overpotential of 320 mV, a high turnover frequency of 0.146 S1-, and a long-term operational stability (over 100 h of continuous operation).