Photocatalytic reduction of carbon dioxide using Co3O4 nanoparticles under visible light irradiation

Production of Methanol from Aqueous CO2 by Using Co3O4 Nanostructures as Photocatalysts

“…Though this material has been widely used for water splitting and water oxidation, this is the first time MeOH production is reported when Co 3 O 4 is used as a photocatalyst in a system as described herein. It is noteworthy that the reaction product obtained here is different from those reported in the two previous works using Co 3 O 4 as a photocatalyst, which at the same time are different from each other [40,41]. This apparent discrepancy may be explained, since different excitation conditions were used in every report: (i) In the work of Mendoza et al [40], the irradiation was carried out using a small window of the visible spectrum (510 to 620 nm); the light intensity in the reaction medium was not reported.…”

“…It is noteworthy that the reaction product obtained here is different from those reported in the two previous works using Co 3 O 4 as a photocatalyst, which at the same time are different from each other [40,41]. This apparent discrepancy may be explained, since different excitation conditions were used in every report: (i) In the work of Mendoza et al [40], the irradiation was carried out using a small window of the visible spectrum (510 to 620 nm); the light intensity in the reaction medium was not reported. (ii) In the report of Huang et al [41], a Xe lamp was used to irradiate the reaction system at an intensity of 9 mW/cm 2 and the photoelectrode was polarized at 0.9 V (vs. SCE) during the experiments.…”

“…In addition, the preparation of different sizes and shapes of this material could potentially enhance the photocatalytic activity, since the optical properties may change and the area and surface defects of the material can increase with regard to its bulk counterpart. Despite the ad hoc properties of this material, only two studies have been reported regarding nanostructured Co 3 O 4 as an active photocatalyst for CO 2 reduction [40,41]. Formic acid and formaldehyde were considered as major products for CO 2 reduction assisted by randomly oriented Co 3 O 4 nanocrystals [40], while formate was the only product using highly texturized {121} nanostructured Co 3 O 4 [41].…”

“…Despite the ad hoc properties of this material, only two studies have been reported regarding nanostructured Co 3 O 4 as an active photocatalyst for CO 2 reduction [40,41]. Formic acid and formaldehyde were considered as major products for CO 2 reduction assisted by randomly oriented Co 3 O 4 nanocrystals [40], while formate was the only product using highly texturized {121} nanostructured Co 3 O 4 [41]. However, Mendoza et al [40] only used a small wavelength range in the visible spectrum (510 to 620 nm), neglecting the much wider absorption range (from UV to NIR) of this material.…”

“…Formic acid and formaldehyde were considered as major products for CO 2 reduction assisted by randomly oriented Co 3 O 4 nanocrystals [40], while formate was the only product using highly texturized {121} nanostructured Co 3 O 4 [41]. However, Mendoza et al [40] only used a small wavelength range in the visible spectrum (510 to 620 nm), neglecting the much wider absorption range (from UV to NIR) of this material. In the work of Huang et al [41], the CO 2 photocatalytic reduction was assisted by an external electric potential in a photoelectrochemical cell configuration, adding additional energy to that of the radiation.…”