Abstract
Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel–vanadium-layered double hydroxide that shows a current density of 27 mA cm−2 (57 mA cm−2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel–iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel–vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.
Highlights
Active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; developing highly efficient catalysts to meet industrial requirements remains a challenge
Pure Ni(OH)[2] was successfully synthesized in the simple hydrothermal system without addition of V sources, and the X-ray diffraction pattern supports the formation of pure hexagonal a-Ni(OH)[2] (JCPDS 380715), which exhibits a layered structure constructed from [NiO6] coordinated octahedra connected by sharing their edges
We investigated the electrocatalytic activities of NiV-LDHs and NiFe-LDHs on glassy carbon (GC) electrodes with different Ni content to optimize the composition
Summary
Active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; developing highly efficient catalysts to meet industrial requirements remains a challenge. Besides Fe(III), cobalt is commonly incorporated in nickel hydroxides to construct NiCo-LDHs for water oxidation[13,14,15,16], and the resulting NiCo-LDHs show promising catalytic activities; the performance is relatively low compared with the reported NiFe-LDHs under identical conditions[9]. More earth-abundant metal elements have been incorporated into Ni(OH)[2] to explore novel LDHs for water oxidation, for example, recently Koper and co-workers[17] investigated a series of Ni-based double hydroxides with Cr, Mn, Fe, Co, Cu and Zn for water oxidation, and among these candidates NiFe-LDH still appears as the most promising and shows the best activity. Without need for exfoliation or hybridization with other materials, the resulting monolayer NiV-LDH catalyst exhibits comparable activity to the best-performing NiFe-LDH for water oxidation in alkaline electrolyte. The Ni 2p spectrum presents two main structures, resulting from the spin–orbit splitting of the p orbital that are assigned as Ni 2p3/2 (850 À 870 eV region) and Ni 2p1/2
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