Shape-controlled synthesis of Cu₂O nanoparticles with single-digit nanoscale void space via ionic liquid/metal sputtering and their photoelectrochemical properties

Abstract

Hollow copper(I) oxide (Cu2O) nanoparticles (NPs) with a diameter of 7.0 ± 1.3 nm were synthesized by sputter deposition of Cu in a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), followed by the oxidation of Cu NPs in EMI-BF4 by prompt heating at 373 K in air. The void space was 2.3 ± 0.7 nm in size, and the shell thickness was estimated to be 2.4 nm. The structure was presumably produced by the Kirkendall effect at the nanoscale. Core–shell-structured Cu@Cu2O NPs and solid Cu2O NPs were also synthesized by changing the oxidation conditions. From the action spectra of their cathodic photocurrents, the optical bandgap of the Cu2O phase in these NPs was estimated to be 2.51–2.56 eV, which is larger than that of bulk Cu2O (2.1 eV). The photoelectrochemical activities of the hollow or spherical Cu2O NPs were higher than those of the core–shell Cu@Cu2O NPs.

Electrocatalyst Fabrication Using Metal Nanoparticles Prepared in Ionic Liquids

“…Interestingly, combining a less noble metal target and the noble metal salt containing IL, e. g. Ag target and HAuCl 4 /IL, we can prepare AuAg alloy nanoparticles with the substitution reaction between [AuCl 4 ] − and Ag nanoparticle [48] . Subsequent heating process of the metal particles prepared using the IL‐magnetron sputtering method can give opportunities to modify their nanoparticle structure [50,59,60] . For instance, as for In nanoparticle, a thin In 2 O 3 layer is easily formed on the surface of pure In nanoparticle, viz., In metal core‐In 2 O 3 shell nanoparticle, at room‐temperature, but the nanoparticles vary to the hollow In 2 O 3 particles by the heating at 523 K [50] .…”

Sputtering onto liquids: a critical review

“…A wide range of elements has been successfully sputtered onto liquids to create monometallic NPs, including Au [12, 114, 115, 118, 120, 122, 125, 126, 129, 132, 134, 138, 139, 142, 143, 145 -149, 153, 167, 174 -176, 180 -183, 188, 189, 203,204,207,208,210,211,214,216,218,229-238], Ag [11,118,119,123,131,164,175,179,184,185,188,196,205,206, 217, 218, 231-233, 239], Cu [150,155,164,188,189,198,210,230,240,241], Pt [121,133,163,168,169,186,[242][243][244][245], Pd [116,212,231,242,246,247], Fe [11,161,162], In [187], Ni [135] and Mo [20...…”

“…2.3.1 Monometallic NPs: A wide range of elements has been successfully sputtered onto liquids to create monometallic NPs, including Au [ 12 , 114 – 115 118 , 120 , 122 , 125 – 126 129 , 132 , 134 , 138 – 139 142 – 143 145 – 149 153 , 167 , 174 – 176 180 – 183 188 – 189 203 – 204 207 – 208 210 – 211 214 , 216 , 218 , 229 – 238 ], Ag [ 11 , 118 – 119 123 , 131 , 164 , 175 , 179 , 184 – 185 188 , 196 , 205 – 206 217 – 218 231 – 233 239 ], Cu [ 150 , 155 , 164 , 188 – 189 198 , 210 , 230 , 240 – 241 ], Pt [ 121 , 133 , 163 , 168 …”

Plasmonic Ag/Cu/PEG nanofluids prepared when solids meet liquids in the gas phase

“…3,4 The formation of finely dispersed metal NPs was observed, which gave an impetus to the development of this method. [5][6][7][8][9][10][11][12] A downside of the methodology is that only liquids with low equilibrium vapor pressure can be used; on the other hand, the method is beneficial in avoiding multiple chemical protocols and purification steps, providing a platform for ultrapure metal/host medium interaction unmediated by the presence of linkers or chemical residues. Recently, more complex systems have been proposed that combine two or several metals to produce alloy nanofluids such as Ag-Au, [13][14][15][16][17] Pt-Au, [18][19][20] Pd-Au, 21,22 Au-Cu, 12,23,24 Ag-Pt, 9 Cu-Pt, 25 Ru-Au, Ru-Cu, Ru-Au-Cu, 12 CoCrCuFeNi (high entropy alloy).…”