Synthesis of ultrathin PdSe2 flakes for hydrogen evolution reaction

Abstract Two-dimensional (2D) palladium diselenide (PdSe2) has demonstrated great promise in electronics and optoelectronics due to its remarkable air stability, appealing carrier mobility, and controllable bandgap. However, realizing the synthesis of 2D PdSe2 remains still a daunting challenge. Herein, high-quality, ultrathin (∼2.2 nm) 2D PdSe2 flakes are achieved on mica substrates through a NaCl-assisted ambient-pressure chemical vapor deposition method. We systematically probe the crystal quality and optical characteristics in PdSe2 using scanning transmission electron microscopy, angle-resolved polarized Raman spectroscopy, and second harmonic generation characterizations. Impressively, the transferred PdSe2 flakes on Au foil, featuring lower overpotential of ∼ 150 mV at 10 mA/cm2, lower Tafel slope of ∼ 70 mV/dec, higher exchange current density of ∼ 85 μA/cm2, and superior stability, display outstanding electrocatalytic performance for hydrogen evolution reaction (HER). This work shows a promising prospect of PdSe2 in electrocatalysis for HER.