Morphology and Phase Engineering of TaS ₂ Nanosheets on Planar Au Substrates Toward Superior Electrocatalytic Property

ABSTRACT Generally, ideal transition metal dichalcogenides (TMDCs) based catalysts should possess vertical nanosheet morphology with abundant edge sites, and superior crystal phase with intrinsically high catalytic property in hydrogen evolution reaction (HER), while the two merits are hard to be combined together. Herein, we report the abnormal vertical growth of high‐density TaS ₂ nanosheets on planar Au substrates, by designing a “precursor‐migration‐prohibited” nucleation and growth process via the atmospheric pressure chemical vapor deposition (APCVD) route. Moreover, we uncover that, high/low growth temperature is the dominant factor for the phase‐selective growth of 2H/1T‐phase TaS ₂ on planar Au substrates. Four typical catalytic systems of vertical or horizontal 2H‐TaS ₂ /Au and 1T‐TaS ₂ /Au are thus achieved, with the vertical 2H‐TaS ₂ /Au catalyst showing ultrahigh electrocatalytic property in HER, featuring rather low overpotential and Tafel slope of ∼53 mV, ∼59 mV/dec, and an ultra‐high exchange current density of ∼1422 µA cm ⁻² . Hereby, this work should provide valuable insights into the synergistic modulation of morphology and phase of metallic TMDCs toward catalytic property upgrade in the energy conversion related fields.