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Nitrogen-doped Graphene Quantum Dots for Remarkable Solar Hydrogen Production
摘要： We synthesized nitrogen (N)-doped graphene quantum dots (N-GQDs) using a top-down hydrothermal cutting approach. The concentration of N dopants was readily controlled by adjusting the concentration of the N source of urea. When N dopants were incorporated into GQDs, visible absorption was induced by C-N bonds, which created another pathway for generating photoluminescence (PL). Time-resolved PL data revealed that the carrier lifetime of GQDs was increased upon doping with the optimized N concentration. The photoelectrochemical properties of N-GQDs towards water splitting were studied, and the results showed that 2N-GQDs prepared with 2 g of urea produced the highest photocurrent. The photocatalytic activity of 2N-GQDs powder photocatalyst for hydrogen production was also examined under AM 1.5G illumination, showing substantial enhancement over that of pristine GQDs. Electrochemical impedance spectroscopy data further revealed a significant improvement in charge dynamics and reaction kinetics, and an increased carrier concentration as a result of N doping.
关键词： Solar Hydrogen Production,Charge Dynamics,Water Splitting,Graphene Quantum Dots,Nitrogen-doped
更新于2025-09-23 15:21:01
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Incorporating graphene quantum dots to enhance the photoactivity of CdSe-sensitized TiO2 nanorods for solar hydrogen production
摘要： This work demonstrated that the incorporation of graphene quantum dots (GQDs) can greatly improve the photoelectrochemical (PEC) efficiency of CdSe-sensitized TiO2 nanorods (TiO2/CdSe), a TiO2-based visible light-responsive photoelectrode paradigm, for solar hydrogen production. For TiO2/CdSe, the accumulated holes at CdSe may induce photocorrosive oxidation to decompose CdSe, deteriorating the long-term stability of photoelectrode and degrading the PEC performance. With the introduction of GQDs, the delocalized holes can further transfer from CdSe to the GQDs, which eases the hole accumulation at the CdSe sites, thus retarding photocorrosion. Compared to the binary TiO2/CdSe photoanode, the ternary TiO2/CdSe/GQDs photoanode displays higher photocurrent and better photostability toward PEC hydrogen production. This superiority can be attributed to vectorial charge transfer and enhanced reaction kinetics provided by the introduction of GQDs. The findings from this work highlight the importance of the introduction of GQDs as a potential solution to the photocorrosion issue of chalcogenide-sensitized semiconductor photoelectrodes.
关键词： photocorrosion,photoelectrochemical efficiency,solar hydrogen production,CdSe-sensitized TiO2 nanorods,graphene quantum dots
更新于2025-09-23 15:19:57
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Electrochemically controlled CdS@CdSe nanoparticles on ITO@TiO2 dual core-shell nanowires for enhanced photoelectrochemical hydrogen production
摘要： Here, we report a novel dual heterostructured photoanode consisting of CdS@CdSe core-shell nanoparticles (NPs) and 1D-structure tin-doped indium oxide (ITO)@TiO2 core-shell nanowires (ITO@TiO2@CdS@CdSe) for highly efficient photoelectrochemical (PEC) hydrogen production. The finely controlled hierarchical core-shell CdS@CdSe sensitization from consecutive electrochemical deposition on the ITO@TiO2 core-shell nanowire has synergistic effects of visible-light utilization and efficient charge transport on the PEC response. The rationally designed dual core-shell heterostructure leads to cascade charge migration throughout the aligned energy band edges with rapid charge extraction through the hierarchical heterostructure of ITO@TiO2@CdS@CdSe, alleviating the crucial charge accumulation. As a result, the dual heterostructured photoanode exhibits a maximum photocurrent density of 20.11 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode (RHE) and a dramatic enhancement in the incident photon-to-current efficiency (IPCE) over the extended absorption spectrum. The time-resolved photoluminescence (TRPL) characterization indicates the realized multiple-band cascade charge migration throughout ITO@TiO2@CdS@CdSe could promote an 8-fold increase in the charge separation efficiency. This rational design of dual-heterojunction-structured photoelectrodes via electrochemical deposition provides a demonstration of modifying conventional light-harvesting photoelectrodes with stagnate solar energy conversion and PEC hydrogen production.
关键词： cascade charge transport,solar hydrogen production,electrochemical core-shell deposition,photoelectrochemical cell,dual heterostructure
更新于2025-09-11 14:15:04
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TiO2 Nanowires-Supported Sulfides Hybrid Photocatalysts for Durable Solar Hydrogen Production
摘要： As the feet of clay, photocorrosion induced by hole accumulation has placed serious limitations on the widespread deployment of sulfides nanostructures for photoelectrochemical (PEC) water splitting. Developing sufficiently stable electrodes to construct durable PEC systems is therefore the key to the realization of solar hydrogen production. Here, an innovative charge transfer manipulation concept based on the aligned hole transport across the interface has been realized to enhance the photostability of In2S3 electrodes toward PEC solar hydrogen production. The concept was realized by conducting compact deposition of In2S3 nanocrystals on the TiO2 nanowires array. Under PEC operation, the supporting TiO2 nanowires functioned as an anisotropic charge transfer backbone to arouse aligned charge transport across the TiO2/In2S3 interface. Because of the aligned hole transport, the TiO2 nanowires-supported In2S3 hybrid nanostructures (TiO2-In2S3) exhibited improved hole transfer dynamics at the TiO2/In2S3 interface and enhanced hole injection kinetics at the electrode surface, substantially increasing the long-term photostability toward solar hydrogen production. The PEC durability tests showed that TiO2-In2S3 electrodes can achieve nearly 90.9 % retention of initial photocurrent upon continuous irradiation for 6 h, whereas the pure In2S3 merely retained 20.8 % of initial photocurrent. This double-gain charge transfer manipulation concept is expected to convey a viable approach to the intelligent design of highly efficient and sufficiently stable sulfides photocatalysts for sustainable solar fuel generation.
关键词： In2S3,interfacial charge dynamics,CdS,photocorrosion,solar hydrogen production
更新于2025-09-04 15:30:14