RESUMEN
Three samples whose growth temperatures were 450°C, 500°C, and 560°C for S E S A M 1, S E S A M 2, and S E S A M 3, respectively, were tested by femto-second time-resolved transient absorption spectroscopy. The results indicate that the carrier dynamics of excited state absorption were dominant, and the lifetimes of carriers trapped by defect levels were about tens of pico-seconds. To further study the influence of carrier dynamics and recovery time of samples by ion-implantation, B + ions of 80 and 130 KeV were implanted into the samples with dose of 1014/c m 2. The modified samples showed a dominance of ultra-fast carrier dynamics of ground-state bleaching and direct recombination, which lasted for hundreds of femto-seconds, over excited state absorption. Additionally, carrier fast trapping was observed to be competitive with the excited state absorption process. After ion-implantation, the carrier dynamics of carrier trapping were enhanced, which contributed to forming an ultra-short laser, while the carrier dynamics of absorption of the excited state were suppressed. The conclusion that defect levels were partially eliminated by B + ion-implantation can be drawn.
RESUMEN
A system containing polyoxometalate ([Co-POM]2-) and [Ru(bpy)3]2+ as constructed for visible-light-induced CO2 conversion to syngas. In diluted CO2, high efficiency of 56.8 mmol g-1 h-1 in syngas production was gained, exceeding that of reported systems with [Ru(bpy)3]2+ participation in similar conditions. Mechanism studies revealed efficient photo-induced charge separation is achieved in the system and CO2 reduction tends to occur on [Ru(bpy)3]2+.
RESUMEN
Halide perovskites have been employed as photocatalysts for CO2 photoreduction due to their excellent optical properties and unique electronic structure. However, their photocatalytic performance is relatively poor. Herein, we demonstrate a new strategy with Mn-doped CsPb(Br/Cl)3 mixed-halide perovskites as catalysts to enhance the efficiency of CO2 photoreduction. By tuning the content of Mn, a series of CsPb(Br/Cl)3:Mn perovskites are obtained and show high efficiency in CO2 conversion to CO and CH4. For the optimum catalyst sample, especially, the yields of CO and CH4 reach 1917 µmol g-1 and 82 µmol g-1 which are 14.2 and 1.4 times higher than those of CsPbBr3. This work provides new insights into improving the reactivity of perovskites in CO2 photoreduction.
RESUMEN
The direct usage of CO2 in the flue gas to produce fuels or chemicals is of great significance from energy-saving and low-cost perspectives, yet it is still underexplored. Herein, we report the photoreduction of CO2 from the simulated industrial exhaust by synergistic catalysis of TEOA and a metal-free composite (COF1-g-C3N4) fabricated via covalently grafting COF1 with g-C3N4. The hydrogen bond interaction between TEOA and hydrazine units on COF1 is detected in diluted CO2, which leads to significantly enhanced light absorption in the whole visible-light region. Also, the photo-induced electrons undergo fast transfer from COF1 to g-C3N4. This kind of dynamic interface with enhanced light absorption and electron transfer effects promotes the photosynthetic yield of syngas to 165.6 µmol·g-1·h-1 with the use of simulated exhaust gas as a raw material directly. The photosynthetic yield of syngas ranks among the highest of known metal-free catalysts in diluted CO2. This work provides a general rule for designing efficient catalysts via a controlled catalytic interface and new insights into the role of TEOA in photochemical CO2 reduction.
RESUMEN
We prepare a novel COF for CO2 photoreduction with 99.9% CO selectivity in aqueous solution without a cocatalyst. DFT shows that the preferential adsorption of H+ on the COF results in increased CO2 adsorption energy providing an anchoring site of CO2, and with the cooperation of an ethylene group, CO2 reduction is triggered.