The exploration of novel electrocatalysts for CO 2 reduction is necessary to overcome global warming and the depletion of fossil fuels. In the current study, the electrocatalytic CO 2 reduction of [Re(CO) 3 Cl( N - N )], where N - N represents 3-(2-pyridyl)-1,2,4-triazole (Hpy), 3-(pyridin-2-yl)-5-phenyl-l,2,4-triazole (Hph), and 2,2′-bipyridine-4,4′ dicarboxylic acidic (bpy-COOH) ligands, was investigated. In CO 2 -saturated electrolytes, cyclic voltammograms showed an enhancement of the current at the second reduction wave for all complexes. In the presence of triethanolamine (TEOA), the currents of Re(Hpy), Re(Hph), and Re(bpy-COOH) enhanced significantly by approximately 4-, 2-, and 5-fold at peak potentials of −1.60, −150, and −1.69 V Ag/Ag+ , respectively (in comparison to without TEOA). The reduction potential of Re(Hph) was less negative than those of Re(Hpy) and Re(COOH), which was suggested to cause its least efficiency for CO 2 reduction. Chronoamperometry measurements showed the stability of the cathodic current at the second reduction wave for at least 300 s, and Re(COOH) was the most stable in the CO 2 -catalyzed reduction. The appearance and disappearance of the absorption band in the UV/vis spectra indicated the reaction of the catalyst with molecular CO 2 and its conversion to new species, which were proposed to be Re- DMF + and Re- TEOA and were supposed to react with CO 2 molecules. The CO 2 molecules were claimed to be captured and inserted into the oxygen bond of Re- TEOA , resulting in the enhancement of the CO 2 reduction efficiency. The results indicate a new way of using these complexes in electrocatalytic CO 2 reduction.

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Visible-light-driven photocatalytic CO2 reduction is a promising approach to addressing the problem of global warming and energy crisis. A Z-scheme photocatalyst comprising of a Re(I) complex and a polymeric semiconductor...

The carotenoid is a natural pigment group, which is gradual of interest because of its essential biological activities and great production potentials such as using low-cost material and easy to apply on a large scale. For further development of natural carotenoid products, in this study, fourteen yellow, red, and orange pigment-producing marine bacterial strains were isolated from 25 seawater samples collected along coasts of Phu Quoc island (Kien Giang province), Vung Tau City (Ba Ria – Vung Tau province), Can Gio district (Ho Chi Minh city), and Thang Binh district (Quang Nam province). These isolates were identified belong to seven genera Micrococcus, Kocuria, Microbacterium, Brevibacterium, Bacillus, Rhodococcus and Exiguobacterium with 96.7% - 100% of 16S rRNA sequences identity. Based on carotenoid producing ability and UV-absorbance profile, three of the isolates including Micrococcus sp. 64A3a (yellow), Exiguobacterium sp. YT09 (orange) and Rhodococcus enclensis strain RSA3 (red) were selected for investigation of carotenoid extraction conditions. Methanol at concentration of 100% with ratio of 1 g bacterial cells/10 mL methanol is suitable conditions for extraction of red, orange and yellow pigments from the isolates.