Electrochemical Synthesis of Tetrahexahedral Rhodium Nanocrystals with Extraordinarily High Surface Energy and High Electrocatalytic Activity

Abstract

Noble metal nanocrystals (NCs) enclosed with high-index facets hold a high catalytic activity thanks to the high density of low-coordinated step atoms that they exposed on their surface. Shape-control synthesis of the metal NCs with high-index facets presents a big challenge owing to the high surface energy of the NCs, and the shape control for metal Rh is even more difficult because of its extraordinarily high surface energy in comparison with Pt, Pd, and Au. The successful synthesis is presented of tetrahexahedral Rh NCs (THH Rh NCs) enclosed by {830} high-index facets through the dynamic oxygen adsorption/desorption mediated by square-wave potential. The results demonstrate that the THH Rh NCs exhibit greatly enhanced catalytic activity over commercial Rh black catalyst for the electrooxidation of ethanol and CO.

Improved ethanol electrooxidation performance by shortening Pd–Ni active site distance in Pd–Ni–P nanocatalysts

“…Direct fuel cells have been recognized as a promising future power source due to advantages, including environmental aspects, facile storage, easy refilling and high power density1234567. However, the lack of active and durable anode catalysts has greatly limited the large-scale commercialization of direct fuel cells.…”

“…However, the lack of active and durable anode catalysts has greatly limited the large-scale commercialization of direct fuel cells. So far, platinum (Pt) has been considered as one of the best catalysts and exclusively utilized in fuel cells23456, but they suffer from high cost and poor carbon monoxide (CO) tolerance8910. Alloying Pt with less expensive oxophilic metals ( M ) such as gold (Au), silver (Ag) and especially nonprecious 3d transition metals11121314 is an effective route to improve CO tolerance and catalytic activity of catalysts, owing to the synergistic and electronic structure alteration mechanism15161718192021222324.…”

Mesoporous metallic rhodium nanoparticles

“…For example, Yu et al . has shown that the convex Rh nanocrystals bound by {830} facets exhibit higher activity for ethanol electro-oxidation than irregular Rh nanoparticles, as well as commercial Rh black41. Huang and co-authors pointed out that wavy Rh nanowires have numerous structural defects/grain boundaries that are responsible for high catalytic activity42.…”

Synthesis of single-crystal hyperbranched rhodium nanoplates with remarkable catalytic properties

“…Importantly, these catalysts exhibited remarkably different current density in the oxygen adsorption/desorption region (0.10-0.80 V). It is well-known that the low-coordinated atoms such as steps, kinks, or structural defects can greatly enhance the oxygen adsorption, thus resulting in large oxygen adsorption/desorption currents [31,40]. All the hyperbranched Rh triangle nanoplates showed larger oxygen adsorption/desorption currents than the commercial Rh black, with Rh branch-6:2 exhibiting the largest current value.…”

“…On the other hand, Rh is an important functional material with excellent catalytic performances in a wide variety of important applications such as hydrogenation, hydroformylation, CO oxidation, NO x reduction, and fuel cell-related reactions [28][29][30][31]. In the last decade, great efforts have been made to improve the catalytic properties of this noble metal by tailoring the morphologies and surface structures of Rh NCs [32][33][34][35][36][37][38][39][40].…”