Ionic‐Liquid‐Functionalized Copper Oxide Nanorods for Photocatalytic Splitting of Water

Abstract

Thin films of imidazolium (Im) ionic liquids with bis(salicylato)borate (BScB) and hexafluorophosphate (PF6−) anions were grafted onto copper oxide (CuO) nanorods. Chemical and structural features of ionic‐liquid‐functionalized CuO (CuO−IL) nanorods were examined by X‐ray photoelectron spectroscopy, FTIR spectroscopy, XRD, and high‐resolution TEM analyses. The CuO−IL nanorods were demonstrated to be efficient photocatalysts for the splitting of water under visible‐light irradiation without using any sacrificial agent. The pristine CuO nanorods could not split water, whereas CuO−IL nanorods exhibited excellent photocatalytic activities and produced 1827 and 1082 μmol of hydrogen in 2 h with 20 mg of CuO−ImBScB and CuO−ImPF6 as photocatalysts, respectively. The photocatalytic activity of the CuO−IL nanorods was attributed to the synergistic effect of ionic‐liquid thin films and CuO nanorods. The trapping of photoinduced charge carriers by ionic liquids inhibits the recombination process, and consequently, the CuO nanorods facilitate the water‐splitting reaction. The CuO−IL photocatalysts were efficiently recycled without loss of catalytic activity, which revealed the stability of the ionic‐liquid thin films grafted on the CuO nanorods.

Highly Efficient Visible‐Light‐Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl3‐Based Ionic Liquids as Homogeneous Photocatalysts

“…Therefore, hydrogen production could efficiently proceed, and a reasonable yield (38.4 mmol h À 1 g À 1 ) was noticed. [24,48,49] Moving on, the increase of [OMIM]Br/FeCl 3 molar ratio from 0.5 : 1 to 1 : 1 could greatly improve the hydrogen productivity rate to reach 243.2 mmol h À 1 g À 1 . The detection of such noticeable hydrogen yield is of strong relevance to the visible light absorption edges of this photocatalyst and its energy bandgap.…”

“…[95] Also, Gusain et al grafted thin films of imidazolium-based ILs onto CuO nanorods, which served as dynamic visible-light-driven photocatalysts. [48] Moreover, Souza et al introduced a novel pathway to synthesize Ta 2 O 5 photocatalysts via the hydrolysis of imidazolium tantalate ILs, which acted as a precursor for the Ta 2 O 5 nanoparticles. [96] The detailed description of photocatalytic water splitting conditions and hydrogen productivity of these research works are displayed in Table 2.…”

Shape tailored Pd nanoparticles’ effect on the photocatalytic activity of commercial TiO 2

“…By the irradiation with light/energy of an aqueous photocatalyst suspension, electron-hole pairs are generated and involved in a succession of redox processes. Large number of semiconductor-photocatalysts have been already reported; from the most studied titanium dioxide [4,5] to other materials with potential photocatalytic properties, like tungsten trioxide [6,7], zinc oxide [8], tin dioxide [9] and copper (II) oxide [10]. Titanium dioxide is the most frequently used semiconductor photocatalyst because of its several beneficial prop-erties: physical and chemical stability, non-toxicity, safety, low cost, and resistance to photocorrosion.…”

Fabrication of Visible‐Light‐Responsive InVO4 for Photoreduction of CO2

“…Much of work to date for photocatalytic reduction of CO 2 had been done over TiO 2 owing to its suitable electronic properties and nontoxicity but due to wider band gap which falls in UV region and massive recombination of generated electron hole pair, drove attention towards the development of visible light active semiconductors to maximize the use of visible light solar energy spectrum. Various visible light active catalysts such as Fe 2 O 3 , Cu 2 O, CuO, Bi 2 S 3 , Bi 2 WO 6 , InTaO 4 , InVO 4 , MoS 2 , CaIn 2 O 4 , InNbO 4 and InMO 4 (M=V, Nb, Ta) had been synthesized recently for solar energy utilization. The solar‐active catalysts which have been reported for CO 2 photoreduction, most of them suffer from low conversion efficiency, uncontrollable selectivity, instability and incapability to completely suppress the competing hydrogen evolution reaction in the presence of water .…”