Covalent organic frameworks (COFs) have emerged as a promising light-harvesting module for artificial photosynthesis and photovoltaics. For efficient generation of free charge carriers, the ...donor-acceptor (D-A) conjugation has been adopted for two-dimensional (2D) COFs recently. In the 2D D-A COFs, photoexcitation would generate a polaron pair, which is a precursor to free charge carriers and has lower binding energy than an exciton. Although the character of the primary excitation species is a key factor in determining optoelectronic properties of a material, excited-state dynamics leading to the creation of a polaron pair have not been investigated yet. Here, we investigate the dynamics of photogenerated charge carriers in 2D D-A COFs by combining femtosecond optical spectroscopy and non-adiabatic molecular dynamics simulation. From this investigation, we elucidate that the polaron pair is formed through ultrafast intra-layer hole transfer coupled with coherent vibrations of the 2D lattice, suggesting a mechanism of phonon-assisted charge transfer.
The solar‐driven catalytic reduction of CO2 to value‐added chemicals is under intensive investigation. The reaction pathway via *OCHO intermediate (involving CO2 adsorbed through O‐binding) usually ...leads to the two‐electron transfer product of HCOOH. Herein, a single‐atom catalyst with dual‐atom‐sites featuring neighboring Sn(II) and Cu(I) centers embedded in C3N4 framework is developed and characterized, which markedly promotes the production of HCHO via four‐electron transfer through the *OCHO pathway. The optimized catalyst achieves a high HCHO productivity of 259.1 µmol g−1 and a selectivity of 61% after 24 h irradiation, which is ascribed to the synergic role of the neighboring Sn(II)–Cu(I) dual‐atom sites that stabilize the target intermediates for HCHO production. Moreover, adsorbed *HCHO intermediate is detected by in situ Fourier transform infrared spectroscopy (CO stretches at 1637 cm−1). This study provides a unique example that controls the selectivity of the multi‐electron transfer mechanisms of CO2 photoconversion using heteronuclear dual‐atom‐site catalyst to generate an uncommon product (HCHO) of CO2 reduction.
A heteronuclear dual‐atom site Sn(II) and Cu(I) photocatalyst embedded in the g‐C3N4 framework is fabricated to selectively produce formaldehyde from CO2 reduction under visible light. The optimized catalyst (Sn:Cu precursor mass ratio of 3:1) exhibits a high HCHO productivity of 259.1 µmol g−1 and a selectivity of 61% after 24 h visible light irradiation.
Conductive metal-organic frameworks are an emerging class of three-dimensional architectures with degrees of modularity, synthetic flexibility and structural predictability that are unprecedented in ...other porous materials. However, engendering long-range charge delocalization and establishing synthetic strategies that are broadly applicable to the diverse range of structures encountered for this class of materials remain challenging. Here, we report the synthesis of K
Fe
(BDP)
(0 ≤ x ≤ 2; BDP
= 1,4-benzenedipyrazolate), which exhibits full charge delocalization within the parent framework and charge mobilities comparable to technologically relevant polymers and ceramics. Through a battery of spectroscopic methods, computational techniques and single-microcrystal field-effect transistor measurements, we demonstrate that fractional reduction of Fe
(BDP)
results in a metal-organic framework that displays a nearly 10,000-fold enhancement in conductivity along a single crystallographic axis. The attainment of such properties in a K
Fe
(BDP)
field-effect transistor represents the realization of a general synthetic strategy for the creation of new porous conductor-based devices.
The successful development of a photocatalyst/biocatalyst integrated system that carries out selective methanol production from CO2 is reported herein. The fine-tuned system was derived from a ...judicious combination of graphene-based visible light active photocatalyst (CCG-IP) and sequentially coupled enzymes. The covalent attachment of isatin-porphyrin (IP) chromophore to chemically converted graphene (CCG) afforded newly developed CCG-IP photocatalyst for this research endeavor. The current work represents a new benchmark for carrying out highly selective methanol formation from CO2 in an environmentally benign manner.
The combination of excellent electronic properties and thermal stability positions orange‐derived graphene quantum dots (GQDs) as promising materials for solar light‐based applications. Researchers ...are actively exploring their potential in fields such as photovoltaics, photocatalysis, optoelectronics, and energy storage. Their abundance, cost‐effectiveness, and eco‐friendly nature further contribute to their growing relevance in cutting‐edge scientific research. Furthermore, only GQDs are not much more effective in the UV‐visible region, therefore, required band gap engineering in GQDs material. In this context, we designed GQDs‐based light harvesting materials, which is active in UV‐visible region. Herein we synthesized GQDs coupled with 2,6‐diaminoanthrquninone (AQ), that is, GQDs@AQ light harvesting photocatalyst the first time for the oxidation of sulfide to sulfoxide under visible light. For the integrating reactions of sulfide in aerobic conditions under visible light by GQDs@AQ photocatalyst exhibit utmost higher photocatalytic activity than simple GQDs due to low molar extinction coefficient and slow recombination charges. The use of GQDs@AQ light harvesting photocatalyst, showed the excellent organic transformation efficiency of sulfide to sulfoxide with excellent yield (94%). The high efficiency and excellent yield of 94% indicate the effectiveness of GQDs@AQ as a photocatalyst for these specific organic transformations.
This graphical represents the photocatalytic oxygenation of sulfide compounds via GQDs@AQ photocatalyst for environmental remediation and chemical synthesis. In this study, we investigate the use of solar light and a novel catalyst consisting of Graphene Quantum Dots (GQDs) decorated with an ingeniously designed aqueous quantum (AQ) system for efficient sulfide oxygenation.
ABSTRACT
To minimize the ever‐increasing global warming and environmental problems, the conversion of atmospheric CO2 into value‐added solar chemicals/fuels is one of the most challenging tasks. As a ...means to accomplish this, herein we have synthesized first time novel in situ selenium‐doped polyimide frameworks (Se‐PIFs) photocatalyst via thermal co‐polymerization approach between melem (M) and perylene 3, 4, 9, 10‐tetracarboxylic dianhydride (PTDA) along with selenium (Se) as a dopant. The Se‐PIFs photocatalyst shows outstanding photocatalytic stability and activity for high solar fuel production (HCOOH ~ formic acid) from CO2. The solar light active Se‐PIFs photocatalyst was demonstrating the ~ 10‐fold higher photo‐conversion of CO2 to formic acid with yields of 250. 6 μmol. The current work is providing a facile and scalable avenue as well as sheds light on creating a new route for in situ judicious design highly efficient Se‐PIFs photocatalyst. The outcome is a benchmark instance for the use of selenium‐doped polyimide frameworks as a highly practical and efficient solar light active photocatalyst for carrying out the selective production of formic acid from environmental CO2.
The graphic depicts the NADH regeneration and formic acid (HCOOH) production from environmental CO2 using newly designed metal‐free selenium‐doped polyimide frameworks (Se‐PIFs) photocatalyst under solar light irradiation via artificial photosynthetic route. The Se‐PIFs photocatalyst is found to be more efficient for NADH regeneration and formic acid production with high yield. The produced NADH and formic acid are demonstrated the importance in many industrial and pharmaceutical applications.
Aloe vera‐derived graphene (ADG) coupled system photocatalyst, mimicking natural photosynthesis, is one of the most promising ways for converting solar energy into ammonia (NH3) and nicotinamide ...adenine dinucleotide (NADH) that have been widely used to make the numerous chemicals such as fertilizer and fuel. In this study, we report the synthesis of the aloe vera‐derived graphene‐coupled phenosafranin (ADGCP) acting as a highly efficient photocatalyst for the generation of NH3 and regeneration of NADH from nitrogen (N2) and oxidized form of nicotinamide adenine dinucleotide (NAD+). The results show a benchmark instance for mimicking natural photosynthesis activity as well as the practical applications for the solar‐driven selective formation of NH3 and the regeneration of NADH by using the newly designed photocatalyst.
In this study, the utilization of solar light irradiation enables the generation and regeneration of ammonia and NADH using an aloe vera‐derived graphene‐coupled phenosafranin (ADGCP) photocatalyst. The results show the remarkable efficiency and environmental friendly nature of the ADGCP system, offering the promising way to solve worldwide issues related to sustainable chemical synthesis and energy production.
Functionalized graphene quantum dots (fGQDs) as visible‐light‐harvesting photocatalysts for solar fuel production from CO2 is explored for the first time. The highly efficient light‐harvesting fGQDs ...photocatalyst upon integration with the biocatalyst performs highly selective CO2 reduction to formic acid. The results are a benchmark example of GQD based materials as photocatalysts for selective production of solar fuels from CO2 and opens up possibilities for greener synthesis of other value added chemicals.
Light harvesting with quantum dots: The successful development of functionalized graphene quantum dots (fGQDs) as visible‐light‐harvesting photocatalysts for solar fuel production from CO2 is explored for the first time.
Abstract
Sulfur‐doped Eosin‐B (SDE‐B) photocatalysts were synthesized for the first time utilizing sublimed sulfur (S
8
) as a dopant in an in situ thermal copolymerization technique. Sulfur doping ...not only increased Eosin‐B (E‐B) absorption range for solar radiation but also improved fixation and oxygenation capabilities. The doped sulfur bridges the S‐S bond by substituting for the edge bromine of the E‐B bond. The improved photocatalytic activity of SDE‐B in the fixation and oxygenation of NAD
+
/NADP
+
and sulfides using solar light is attributed to the photo‐induced hole of SDE‐B's high fixation and oxygenation capacity, as well as an efficient suppression of electron and hole recombination. The powerful light‐harvesting bridge system created using SDE‐B as a photocatalyst works extremely well, resulting in high NADH/NADPH regeneration (79.58/76.36%) and good sulfoxide yields (98.9%) under solar light. This study focuses on the creation and implementation of a sulfur‐doped photocatalyst for direct fine chemical regeneration and organic transformation.
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