Self-Templating Construction of Porous CoSe₂ Nanosheet Arrays as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Abstract

Developing low-cost, high performance, stable non-noble bifunctional electrocatalysts for overall water splitting is of great importance for future energy supplement. Despite recent advances in the synthesis of transition metal selenide nanostructures, the fabrication of porous nanosheet based binder-free electrode with more active sites remains a major challenge. Herein, the self-templating construction of a porous CoSe2 nanosheet array on carbon cloth (p-CoSe2/CC) has been reported by vapor selenizing the preprepared α-Co­(OH)2 nanosheet array precursor. Arising from large active surface area, fast diffusion of generated gas and strong structural stability, the as-obtained p-CoSe2/CC can serve as an efficient bifunctional electrocatalyst for both OER and HER in alkaline electrolyte, with a current density of 10 mA cm–2 at overpotential of 243 mV for OER and 138 mV for HER, respectively. Moreover, when p-CoSe2/CC is assembled as an alkaline electrolyzor, it only needs a cell voltage of 1.62 V at 10 mA cm–2 and shows excellent long-term stability of 20 h. The versatile fabrication strategy with self-templated porous structure proves a new way to construct other advanced metal selenide for energy conversion and storage.

Hierarchical 0D−2D Co/Mo Selenides as Superior Bifunctional Electrocatalysts for Overall Water Splitting

“…Therefore, the CoSe 2 /MoSe 2 catalyst exhibits improved HER performance benefiting from the synergistic effect. The catalyst of Pt/C illustrates an overpotential (η 10 ) (59 mV) and Tafel slope (36.9 mV•dec −1 ) in 1 M KOH that are similar to those in other literatures (Chen et al, 2018b;Wan et al, 2018). Moreover, the overpotential of CoSe 2 /MoSe 2 is superior to those of recently reported selenide catalysts such as NiSe NWs/Ni Foam (96 mV) (Tang et al, 2015), EG/cobalt selenide/NiFe-LDH (260 mV) (Hou et al, 2016), o-CoSe 2 /P (104 mV) (Zheng et al, 2018), CoSe 2 NCs (520 mV) (Kwak et al, 2016), Co 0.75 Ni 0.25 Se/NF (106 mV) (Liu et al, 2019), 1T MoSe 2 /NiSe (120 mV) (Zhang et al, 2019), and SWCNTs/MoSe 2 (219 mV) (Najafi et al, 2019) (Table S1).…”

Recent advances in transition metal-based electrocatalysts for alkaline hydrogen evolution

“…Hybridizing with conductive carbon-based materials/substrates (e.g., carbon cloth, 180 (Figure 12d and e). Such regulated electronic structure vastly enhanced the intrinsic electrocatalytic activity of NiCoSe 2 .…”

Ultrathin Two‐Dimensional Metal‐Organic‐Framework‐Derived CoO/Nitrogen and Sulfur Co‐doped Ultrathin Porous Carbon Nanoplates for Highly Efficient Water Electrolysis

“…With the cell potential increasing from 1.46 V to 1.63 V, the current of water electrolysis also increases from 0 to 10 mA cm −2 , and numerous H 2 and O 2 bubbles are produced from the surface of the carbon cloth (the inset in Figure a). This potential can be competitive with some other Co‐based water electrolyzers (Figure c) . The stability test (Figure b) shows that the cell potential only increases 30 mV after continuous testing at 10 mA cm −2 for 20 h, indicating a high stability.…”

“…Additionally, porous structure exists in the CoO/N‐S‐UPCNPs‐600. Such porous structure will favor the improvement of electrocatalytic activity due to the exposure of more catalytic sites . Moreover, every nanoplate is assembled with smaller nanoplates with the size of 38–100 nm (Figure b).…”

“…Such porous structure will favor the improvement of electrocatalytic activity due to the exposure of more catalytic sites. [14] Moreover, every nanoplate is assembled with smaller nanoplates with the size of 38-100 nm (Figure 3b). The inset in Figure 3b indicates that the thickness of the smaller nanoplate is about 2.4 nm.…”