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A novel and facile post-grafting strategy, via a Schiff base chemical reaction between aldehyde and −NH 2 groups within NH 2 -MIL-125(Ti) has been developed to construct aromatic heterocycle-grafted metal organic frameworks (MOFs) photocatalysts. The improved conjugated system in MOFs showed lower band gaps and their excellent catalytic activities were manifested by selective oxidation of alcohols to corresponding aldehydes under visible light irradiation with high conversion and selectivity. Density functional theory (DFT) was applied for simulating the band gaps and electron orbits of heterocycle-grafted MOFs. The post-synthetic aromatic heterocycles in the MOFs network did not influence the original framework, but effectively expanded its π-delocalized system and promoted the separation and transfer of photo-excited charge carriers. As a result, the aromatic heterocycle-grafted MOFs exhibit significantly enhanced visible-light photo-catalytic activity for selective oxidation of alcohols over pristine NH 2 -MIL-125(Ti). Especially, the NH 2 -MIL-125(Ti) grafted by 2-quinolinecarboxaldehyde and 3-thiophenecarboxaldehyde showed better performance (more than 85% conversion of benzyl alcohol) due to the excellent photon adsorption and charge carriers transfer of aromatic heterocycles grafted on MOFs. This general grafting strategy can be utilized to graft large numbers of aromatic rings with different molecular structures onto NH 2 -MIL-125(Ti). [ABSTRACT FROM AUTHOR]

Photochemical devices show great potential in applications ranging from electrical energy storage to future smart grids. Here, we report a metal-free composite film cell based on carbon dots (CDots) and polyaniline (PANI), which could achieve 24/7 discharge and photo-charging in seawater. CDots/PANI film cell has an open-circuit-voltage (OCV) of 0.95 V, a maximum power density of 380 mW m2, and the ability to discharge continuously for 40 h under solar irradiation of AM 1.5 G. It couples the reduction reaction of PANI, and the CDot-catalyzed oxygen reduction reactions (ORR) during discharge. While the light-induced CDot-catalyzed oxygen evolution reaction (OER) and the reduction reaction of PANI during charging. In particular, in-situ TPV tests were used to verify the effect of the light-induced OER and the kinetic properties of the catalyst on the charge transfer at the interface. We believe this research may provide new ideas for sustainable energy conversion and storage. Carbon dots-based film cell can achieve 24/7 discharge and photo-charging in seawater, is capable of storing energy and utilizes the redox reaction of polyaniline, the ORR/OER catalyzed by carbon dots for discharge and charging, and TPV tests were used to explore the OER process and catalytic mechanism during charging. [Display omitted] [ABSTRACT FROM AUTHOR]

Photocatalytic water-splitting to generate hydrogen (H 2) and hydrogen peroxide (H 2 O 2) is a green and renewable method to convert solar energy into chemical energy. The water impurity in organic solvents is usually hard to be removed. Here, we firstly used an organic semiconductor (DAnTMS) synthesized from 9,10-dibromoanthracene and trimethylsilylacetylene to convert the water impurity in organic solvent into H 2 and H 2 O 2 by photocatalysis. Under visible light, for 300.0 μL water in 20.0 mL methyl cyanide (MeCN) system, the DAnTMS catalyst can produce H 2 and H 2 O 2 with rate of 245.9 μmol g−1 h−1 and 3923.4 μmol g−1 h−1, respectively. Furthermore, a practical photocatalytic experiment was performed in 20.0 mL commercially available MeCN (99.8%, H 2 O ≤ 0.01%) with 10.0 mg DAnTMS as catalyst, in which, the total 15.4 μmol H 2 and 176.7 μmol H 2 O 2 were generated after 12 h reaction, suggesting the water impurity in MeCN was completely removed. In present catalytic system, on DAnTMS, O 2 and H 2 O are reduced into H 2 O 2 and H 2 , respectively, while, H 2 O is oxidized into H 2 O 2 through a 2e- pathway. An organic semiconductor was used to convert the water impurity in MeCN (98%, H 2 O ≤ 0.01%) into H 2 and H 2 O 2 by photocatalysis. [Display omitted] • DAnTMS was used to convert the water impurity in organic solvent into H 2 and H 2 O 2 by photocatalysis. • TPV tests were used to explore the half-reaction process and catalytic mechanism. • The extrapolation was applied on the TPV curves. [ABSTRACT FROM AUTHOR]

Hematite is an excellent catalyst for solar water splitting but its practical performance is still low. In this work, a hetero phase of β-Fe 2 O 3 was firstly introduced in α-Fe 2 O 3 to optimize the internal structure, which can synergistically work with oxygen vacancy to enhance the charge extraction, facilitate the charge transport, and suppress the electron-hole recombination. As a result, the obtained hematite exhibits a high initial photocurrent of 2.72 mA/cm2 at 1.23 V vs. RHE, and can be well coupled with various further modifications such as P, Hf, and FeNiOOH to achieve an excellent photocurrent of 5.24 mA/cm2 at 1.23 V vs. RHE with a good stability over 100 h. Moreover, it can realize a benchmark solar-to-hydrogen conversion efficiency of 5.3% when connected to a commercial Si solar cell. The low cost, efficient, and stable hematite-based photoanodes may pave the way for practical solar water splitting. [Display omitted] • β-Fe 2 O 3 in hematite has been firstly reported to improve the PEC performance. • Hetero phase and oxygen vacancy can effectively enhance the bulk charge utilization. • It can achieve a high and stable photocurrent of 5.24 mA/cm2 at 1.23 V RHE. • A benchmark solar-to-hydrogen conversion efficiency of 5.3% can be obtained. [ABSTRACT FROM AUTHOR]