Ru Nanoparticles Supported on Oxygen‐Deficient 3DOM BiVO₄: High‐Performance Catalysts for the Visible‐Light‐Driven Selective Oxidation of Benzyl Alcohol

Abstract

Developing novel photocatalysts for green synthesis of important organic intermediates under mild conditions is of great significance in industry. In this work, we synthesized the oxygen-deficient three-dimensionally ordered macroporous (3DOM) BiVO 4 -supported nanosized Ru (xRu/3DOM BiVO 4 , x = 0.24-2.16 wt %) catalysts by the polymethyl methacrylatetemplating, ethylene glycol reduction, and post-thermal treatment methods. Physicochemical properties of the materials were characterized using the various techniques, and their catalytic activities for the visible-light-driven selective oxidation of benzyl alcohol to benzaldehyde were measured. It is found that the Ru nanoparticles (NPs) with a size of 1.2-1.5 nm were uniformly dispersed on the surface of 3DOM BiVO 4 , which gave rise to a significant enhancement in photocatalytic activity.Benzyl alcohol conversion first went up and then dropped down with the rise in loading of Ru NPs. The 0.95Ru/3DOM BiVO 4 À Ar-300 sample was thermally treated in an Ar flow at 300°C for 4 h showed the highest benzyl alcohol conversion (78 %) with a benzaldehyde selectivity of 100 % (benzaldehyde formation rate was 1380 μmol/(g h) after 6 h of illumination) and good photocatalytic stability. The high dispersion of Ru NPs and formation of oxygen vacancies in 3DOM BiVO 4 improved separation and transfer efficiency of the photogenerated electrons/holes and increased the superoxide radical concentration. In addition, the possible mechanism of benzyl alcohol oxidation over 0.95Ru/3DOM BiVO 4 À Ar-300 was also discussed.

Boosting the catalytic behavior and stability of a gold catalyst with structure regulated by ceria

“…3 In recent years, attention has been paid to the aerobic oxidation of benzyl alcohol (BnOH) in the presence of molecular oxygen or air, mostly using precious and transition metal-based catalysts. [3][4][5] Supported Au nanoparticles (Au NPs) with outstanding surface chemistry were preferentially focused due to their excellent selectivity for heterogeneous oxidations compared with other precious metals. 6,7 However, the conversion and stability of gold catalysts during aqueous reaction still need efficient promotions.…”

Oxidation of Benzyl Alcohol Using Cobalt Oxide Supported Inside and Outside Hollow Carbon Spheres

“…[34][35][36][37] Catalytic oxidation, using air or molecular oxygen in the presence of a heterogeneous catalyst, is a more environmentally friendly approach and this oxidant has also shown good efficiency. [38,39] Many current methods for the oxidation of benzyl alcohol can suffer disadvantages, such as long reaction times and low efficiencies. [33] Oxidation of simple small-chain alcohols is normally easy and straightforward.…”

“…Noble metal catalysts such as Pt, Pd, Au, Rh, Ir and Ru have been investigated for this process and good activity and selectivity have been achieved. [31,38] However, these metals are expensive and, in some cases, require the use of promoters such as NaOH and K 2 CO 3 to control the selectivity during the reaction. [29,42] Non-noble metals like Co, Ni, Fe and Cu are relatively cheaper alternatives that have also been used without the use of promoters and can provide high selectivity.…”

“…Different oxidizing agents have been used for the oxidation of benzyl alcohol, including the use of hydrogen peroxide, manganese dioxide, permanganate and dichromate [34–37] . Catalytic oxidation, using air or molecular oxygen in the presence of a heterogeneous catalyst, is a more environmentally friendly approach and this oxidant has also shown good efficiency [38,39] . Many current methods for the oxidation of benzyl alcohol can suffer disadvantages, such as long reaction times and low efficiencies [33] …”

“…Therefore, the ideal catalyst for this reaction is one that will selectively produce benzaldehyde in large amounts. Noble metal catalysts such as Pt, Pd, Au, Rh, Ir and Ru have been investigated for this process and good activity and selectivity have been achieved [31,38] . However, these metals are expensive and, in some cases, require the use of promoters such as NaOH and K 2 CO 3 to control the selectivity during the reaction [29,42] .…”