Self-Assembled Oligothiophenes for Photocatalytic Hydrogen Production and Simultaneous Organic Transformation

Abstract

Herein, we have fabricated self-assembled semiconducting organic nanomaterials with various morphologies (1Dfiber, 2D-flakes, and 2D-nanosheets) made of small conjugated oligomer 2,2′:5′,2″:5″,2‴-quaterthiophene (α-QTH) by a simple solution-based coprecipitation method. By simply varying the good-solvent-to-bad-solvent ratio, we can critically tune the selfassembly process and eventually can control the intermolecular interactions of the constituent molecules in these self-assembled nanostructures. Different types of self-assembled nanostructures have been utilized for photocatalytic solar H 2 production. The H 2 production efficiencies directly depend on the morphology of selfassembledselfassembled nanomaterials as well as intermolecular interactions of QTH molecules. The overall photocatalytic properties are further correlated with the ongoing photophysical properties by means of detailed steady-state and time-resolved fluorescence spectroscopy and dimer-based time dependent-density functional theory (TD-DFT) calculations. Furthermore, femtosecond transient absorption spectroscopy has been utilized to explore the detailed photoinduced exciton dynamics by global analysis of spectrally resolved pump−probe traces. In addition to that, the overall photocatalytic activities are further supported by an in-depth electrochemical study. Finally, a boost in photocatalytic H 2 production has been observed by using 4-methylbenzyl alcohol (4-MBA) as a specific hole scavenger for the completion of the redox cycle. Therefore, the present system can be utilized for simultaneous solar H 2 production and the specific organic transformation through a green and cost-efficient approach.

Engineering of Solar Energy Harvesting Tb3+-Ion-Doped CdS Quantum Dot Glasses for Photodissociation of Hydrogen Sulfide

“…In this investigation, the analysis of data revealed the average lifetimes of 1305, 771, 643, and 622 μs for as-prepared and heat-treated 2 wt % CdS Q-dots in borosilicate glasses at 550, 575, and 600 °C. The decrease in the average lifetime is attributed to an increase in CdS Q-dot size and thus closer CdS–CdS Q-dot ion–ion interaction, which can result in faster recombination of electron–hole pairs . Moreover, the addition of 0.02 and 0.04 wt % Tb 3+ ions to CdS Q-dots in borosilicate glass also led to a further decrease in the average lifetime with increasing heat treatment temperature as seen in Table .…”

“…Note that the PL lifetimes of the chemically dispersed Q-dots in a borosilicate glass provide insight into the efficiency and stability of photogenerated electrons in the excited state, as discussed by Hong et al and Kommula et al , A short lifetime may lead to reducing photocatalytic activity, as the photogenerated electron–hole pairs may have less time to participate in contributing to the photodissociation of H 2 S via the H + + HS – reaction. Figure S2 illustrates the PL decay curves measured under 450 nm excitation for 2 wt % CdS and 0.04 wt % Tb 3+ -CdS-doped borosilicate glasses heat-treated at various temperatures.…”

Unveiling the role of a ground state charge transfer complex in carbon nanoparticles for highly efficient metal-free solar hydrogen production

“…A detailed description of fs-TAS (ESI †) can be found elsewhere. 59,60 We primarily utilized a 400 nm pump pulse excitation for pure N, P-CNPs and a 530 nm pump pulse excitation for the N, P-CNP (TEOA) adduct, corresponding to their steady-state absorption spectra. Additionally, we have employed 400 nm excitation to investigate the dynamics associated with the blue-edge excitation of the CT state in the N, P-CNP (TEOA) adduct.…”

Self-assembled π-conjugated chromophores: preparation of one- and two-dimensional nanostructures and their use in photocatalysis

“…It is perhaps not surprising that different packings, which usually translate into different morphologies, can lead to dissimilar photocatalytic activity. [51][52][53][54] In one example, a quaterthiophene (QTH) molecule was observed to form crystalline nanorods in a THF/H 2 O mixture (7 : 3 v/v), whereas a nanosheet morphology was noted when a THF solution was injected into H 2 O (Fig. 4c).…”