Metallic Ni₃S₂ Films Grown by Atomic Layer Deposition as an Efficient and Stable Electrocatalyst for Overall Water Splitting

Abstract

We describe the direct preparation of crystalline NiS thin films via atomic layer deposition (ALD) techniques at temperatures as low as 250 °C without postthermal treatments. A new ALD chemistry is proposed using bis(1-dimethylamino-2-methyl-2-butoxy) nickel(II) [Ni(dmamb)] and HS as precursors. Homogeneous and conformal depositions of NiS films were achieved on 4 in. wafers (both metal and oxide substrates, including Au and SiO). The resulting crystalline NiS layers exhibited highly efficient and stable performance as electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline solutions, with a low overpotential of 300 mV and a high turnover frequency for HER and an overpotential of 400 mV for OER (at a current density of 10 mA/cm). Using our NiS films as both the cathode and the anode, two-electrode full-cell electrolyzers were constructed, which showed stable operation for 100 h at a current density of 10 mA/cm. The proposed ALD electrocatalysts on planar surfaces exhibited the best performance among NiS materials for overall water splitting recorded to date.

Facile Dynamic Synthesis of Homodispersed Ni3S2 Nanosheets as a High‐Efficient Bifunctional Electrocatalyst for Water Splitting

“…As displayed in Figure 4d, the corresponding Tafel slope of Ni 3 S 2 /NF-DH is calculated to be 50 mV dec À 1 while that of Ni 3 S 2 /NFÀ SH and NF are 93 and 130 mV dec À 1 , signifying that uniformly growth of Ni 3 S 2 on the foam provides abundant exposed active sites and thereby facilitates the penetration of the electrolyte and water-oxidation the kinetics of reaction. [1b] The examined activities of Ni 3 S 2 /NFÀ DH about two reactions outperforms many other previous sulfide nickel by static hydrothermal means (Table S1), such as Ni 3 S 2 films, [25] Ni 3 S 2 nanosheet [11] and Ni 3 S 2 nanowire. [26] The HER and OER activity for Ni 3 S 2 /NF-DH superior to Ni 3 S 2 /NFÀ SH could be attributed to the uniformity of Ni 3 S 2 crystal grown on substrate surface and the facilitated electronic exchanges.…”

Fe‐Doped Ni3S2 Nanowires with Surface‐Restricted Oxidation Toward High‐Current‐Density Overall Water Splitting

“…For undoped Ni 3 S 2 , the characteristic Raman peaks at 193.6, 216.4, 301.7, and 341.8 cm À 1 can be assigned to one A 1 and three E vibrational modes of Ni 3 S 2 , [38] which are well matched with the corresponding heazlewoodite phase of Ni 3 S 2 . [11,13,15,39] For Fe 13.7% -Ni 3 S 2 , the peaks are all shifted to a lower wavenumber compared to undoped Ni 3 S 2 , revealing the state of NiÀ S bonds was changed by Fe ions doped into Ni 3 S 2 lattices.…”

“…[6][7][8][9] Among these catalysts, nickel-based compounds, e. g. nickel sulfides, have unique configuration and high conductivity, of which abundant NiÀ S and NiÀ Ni bonds can facilitate the production of the intermediate (OOH*) for OER and the adsorbed hydrogen (H*) converted to H 2 for HER, therefore, are employed as promising water splitting electrocatalysts. [10][11][12][13][14][15][16][17] Nickel sulfide with suitable element doping can modulate its electronic and surface structure, hence, significantly enhancing the electrocatalytic performance for OER and (or) HER. Zn, [18] V, [19] Sn, [20] N, [21] Mo, [22] and Fe [23][24][25][26][27][28] elements have been doped in nickel sulfide lattices for promoted OER, HER or overall water splitting electrocatalysis.…”

Effect of Temperature on the Properties of Nickel Sulfide Films Performed by Spray Pyrolysis Technique

“…where G is the crystallite size,  is the wavelength of X-ray (  = 1.5406 A°). However, the dislocation density  of nickel sulfide thin films was calculated from crystallite size by following relation [35]:…”