NiO/NiS Heterostructures: An Efficient and Stable Electrocatalyst for Oxygen Evolution Reaction

Abstract

The intervening barrier to produce hydrogen from water is the frustratingly slow kinetics of the water splitting reaction. In addition, insufficient understanding of the key obstacle of the oxygen evolution reaction (OER) is an obstruction to perceptive design of efficient OER electrocatalysts. In this research, we present synthesis, characterization, and electrochemical evaluation of nickel oxide/nickel sulfide (NiO/NiS) heterostructures and its counterparts nickel oxide (NiO) and nickel sulfide (NiS) as low-cost electrocatalysts for electrochemical water splitting. These electrocatalysts have been characterized using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The NiO/NiS is found to be highly efficient and stable electrocatalyst, which initiates the OER at an amazingly low potential of 1.42 V (vs RHE). The NiO/NiS electrocatalyst provides a current density of 40 mA cm–2 at 209 mV overpotential for OER in 1.0 M KOH with a Tafel slope of 60 mV dec–1, outperforming its counterparts (NiO and NiS) under same electrochemical conditions. These results are better than those of benchmark Ni-based and even noble metal-based electrocatalysts. The continued oxygen generation for several hours with an applied potential of 1.65 V (vs RHE) reveals the long-term stability and activity of NiO/NiS electrocatalyst toward OER. This development provides an attractive non-noble metal, highly efficient, and stable electrocatalyst toward OER.

Direct solvent free synthesis of bare α-NiS, β-NiS and α-β-NiS composite as excellent electrocatalysts: Effect of self-capping on supercapacitance and overall water splitting activity

“…Both αand β-NiS have been studied for supercapacitance and water splitting applications, achieving specific capacitances as high as 1122 F g − 1 23 , and good catalytic performance 25,26 . In pursuit of better cycling stability and overall electrochemical performance, much effort has been directed towards the formation of heterostructures of NiS and other active materials such as Ni 2 P 30 , graphine oxide 31 , and metal chalcogenides [32][33][34] .…”

Pyrolysis‐Synthesized g‐C3N4/Nb2O5 Nanocomposite for Enhanced Photocatalytic Activity under White LED Light Irradiation

“…From the higher resolution C 1s spectrum, the peak at 284.7 eV is attributed to characteristic sp 2 C-C bonds and another peak at approximately 289.4 eV is related to NÀ C-N organization of probable triazine rings excited in the lamellar g-C 3 N 4 (Figure 4a). [43] The N1s spectrum shows two peaks at 399.8 eV corresponded to sp 2 nitrogen in the CÀ N-C bond of poly s-triazine ring and a peak at 401.2 eV, is related to the ending amino groups (C-NH 3 ) ( Figure 4b), [46] respectively. The Nb 3d spectrum consists of two divergent doublets and a tiny shoulder peak as shown in Figure 4c.…”

“…[29] To overcome the drawbacks, a number of g-C 3 N 4 based heterojunctions photocatalysts have been recently successfully developed for enhancing photocatalytic activity such as g-C 3 N 4 /TiO 2 , [30] g-C 3 N 4 /WO 3 , [31] g-C 3 N 4 /ZnFe 2 O 4 , [32] g-C 3 N 4 /ZnO, [33] g-C 3 N 4 /Ag 3 PO 4 , [34] g-C 3 N 4 /BiPO 4 , [35] g-C 3 N 4 / Bi 2 WO 6 , [36] g-C 3 N 4 /CdS, [37] g-C 3 N 4 /NiO, [38] g-C 3 N 4 /Cu 2 O, [39] g-C 3 N 4 / Fe 3 O 4 , [40] high absorption coefficient, strength of surface acid sites, bandgap value ranging from 3.1 to 4.0 eV, and sufficient photoactive nature. [42][43] Moreover, the bandgap edge of Nb 2 O 5 (E CB = -0.51 eV, E VB = 2.61 eV) can consistent well with g-C 3 N 4 (E CB = -1.12 eV, E VB = 1.58 eV) to form a heterointersection system that can enable charge carrier separation and lead to improved photocatalytic activity. [44] In Nb 2 O 5 / g-C 3 N 4 heterojunctions, different Nb 2 O 5 ratios were loaded onto g-C 3 N 4 using the hydrothermal method.…”

In-situ surface self-reconstruction in ternary transition metal dichalcogenide nanorod arrays enables efficient electrocatalytic oxygen evolution

“…Transition metal (TM)-based materials, especially nickel-based, as a class of potential substitutes for the precious metal catalysts, have attracted considerable attention in recent years, which can be attributed to their unique electronic structures making them suitable for binding with oxygen-involving intermediates [12][13][14]. Among the most active Ni-based OER catalysts [12,[15][16][17], nickel sulfides (such as NiS [18,19], NiS 2 [20,21], and Ni 3 S 2 [22][23][24]) have been widely explored, where nickel dichalcogenide (ND) phase is notable for its metal-like properties [25][26][27][28]. For example, Feng et al devised high-index faceted Ni 3 S 2 nanosheets formed on nickel foam (NF), which exhibited excellent OER electrocatalytic activity [29].…”