Porous Two-Dimensional Nanosheets Converted from Layered Double Hydroxides and Their Applications in Electrocatalytic Water Splitting

Abstract

Porous materials are of particular interest due to their high surface area and rich edge sites, which are favorable for applications such as catalysis. Although there are well-established strategies for synthesizing porous metal oxides (e.g. by annealing the corresponding metal hydroxides), facile and scalable routes to porous metal hydroxides and metal chalcogenides are lacking. Here, we report a simple and general strategy to synthesize porous nanosheets of metal hydroxides by selectively etching layered double hydroxide (LDH) nanoplate precursors that contain amphoteric metal, and to further convert them into porous metal chalcogenides by a solution method. Using NiGa LDH as an example, we show that the thin nanoplates with high surface accessibility facilitate the topotactic conversion of NiGa LDH to β-Ni(OH) 2 and further to NiSe 2 with porous texture while preserving the sheet-like morphology. The converted β-Ni(OH) 2 and NiSe 2 are highly active for electrocatalytic oxygen evolution reaction and hydrogen evolution reaction (HER), respectively, which demonstrates the applications of such high surface area porous nanostructures with rich edge sites. Particularly, the porous NiSe 2 nanosheets exhibited excellent catalytic activity toward HER with low onset overpotential, small Tafel slope, and good stability under both acidic and alkaline conditions. Overall electrochemical water splitting experiments using these porous β-Ni(OH) 2 and NiSe 2 nanosheets were further demonstrated. Our work presents a new strategy to prepare porous nanomaterials, and to further enhance their catalytic and other applications.

Selenium‐Enriched Nickel Selenide Nanosheets as a Robust Electrocatalyst for Hydrogen Generation

“…As seen in Figure 3a,t he CF substrate has an egligible HER performance with af eatureless polarization curve.N otably, the Se-rich NiSe 2 -450 electrode achieved acurrent density of 10 mA cm À2 at al ow overpotential of 117 mV (h 10 ), which is lower than those recently reported for other binary pyrite structures. [13,26] This electrode demonstrates the best HER catalytic performance among all synthesized samples,with h 10 values of 125 mV and 129 mV for NiSe 2 -400 and NiSe 2 -500, respectively ( Figure S9). In an attempt to explore these differences between the as-grown NiSe 2 based samples,t he double-layer capacitances (C dl )w ere utilized to estimate the effective electrochemically active area of the solid-liquid interface (Note SIII, Figures S10 a-c and 11 a).…”

Nanostructured catalysts for electrochemical water splitting: current state and prospects

“…Then, it can be aged and converted to anhydrous β-Ni(OH)2 in base or in vacuum environment 209 . Wang et al 211 demonstrated a new strategy to synthesize β-Ni(OH)2 from NiGa LDH nanoplate precursors by selective etching away Ga 3+ ions, which was further converted to NiSe2 by a solution method. Generally, β-NiOOH shows better electrocatalytic activity than γ-NiOOH.…”

Vertically Aligned Porous Nickel(II) Hydroxide Nanosheets Supported on Carbon Paper with Long‐Term Oxygen Evolution Performance

“…In this context, considerable research efforts have recently been de-voted to the search for efficient and inexpensive OER catalysts comprising earth-abundant elements, including transitionmetal oxides, [8][9][10] hydroxides, [11][12][13] perovskites, [14,15] phosphates, [16,17] sulfides, [18,19] and recently reported phosphides. [33][34][35][36][37][38][39][40] For example, Stern and Hu compared the OER performance of bulk Ni(OH) 2 films to that of Ni(OH) 2 nanoparticles and found that the Ni(OH) 2 nanoparticles only neededasmall overpotential (h)o f3 00 mV to deliver ac urrent density of 10 mA cm À2 (h 10 ), and thus, they substantially outperformed bulk Ni(OH) 2 films and demonstratedt he benefito fn anostructuring. Previous work on the OER performance of Ni(OH) 2 was primarily focusedo ne lectrodepositeda nd physically depositedt hin films.…”