Photocatalytic H2 Evolution Research Articles

Modulating Schottky barriers and active sites of Ag-Ni bi-metallic cluster on mesoporous carbon nitride for enhanced photocatalytic hydrogen evolution

The advancement of photocatalysis relies on the development of novel hetero-structured materials with unique architectures. In this study, we successfully synthesized a hetero-structured g-C3N4 (GCN) material with a distinctive surface-interface modification. To further enhance its photocatalytic performance, we optimized the Ag and Ni concentration to maximize the visible light absorption and catalytic active sites for hydrogen evolution reactions. By using systematic physicochemical characterizations and density functional theory (DFT) calculations, we elucidated the pivotal role of graphitic carbon nitride (g-C3N4) in facilitating the formation of an efficient charge transfer channel and promoting the effective generation and separation of photo-generated carriers. From the DFT calculations, we also demonstrated that the Ag and Ni nanoparticles provide more efficient visible light absorption and active sites than Ni nanoparticles for water splitting and hydrogen evolution and In-situ TEM exploration. Furthermore, the hetero microstructure consisting of thin g-C3N4 nano scrolls has a crucial role in shortening the migration distance of the carriers, effectively suppressing carrier recombination. Consequently, these extraordinary characteristics resulted in a superior solar light-driven photocatalytic H2 evolution rate of 2507 μmol.h-1.g−1, surpassing the rate achieved by g-C3N4 heterostructures by a remarkable 18.6-folds. Moreover, the apparent quantum efficiency of this hetero-structured material reached an exceptional value of 1.6 % under a 1.5 G air mass filter.

Square-Planar Nickel Bis(phosphinopyridyl) Complexes for Long-Lived Photocatalytic Hydrogen Evolution.

Phosphinopyridyl ligands are used to synthesize a class of Ni(II) bis(chelate) complexes, which have been comprehensively characterized in both solid and solution phases. The structures display a square-planar configuration within the primary coordination sphere, with axially positioned labile binding sites. Their electrochemical data reveal two redox couples during the reduction process, suggesting the possibility of accessing two-electron reduction states. Significantly, these complexes serve as robust catalysts for homogeneous photocatalytic H2 evolution. In a system utilizing an organic photosensitizer and a sacrificial electron donor, an optimal turnover number of 27,100 is achieved in an alcohol-containing aqueous solution. A series of photophysical and electrochemical measurements were conducted to elucidate the reaction mechanism of photocatalytic hydrogen generation. Density function theory calculations propose a catalytic pathway involving two successive one-electron reduction steps, followed by two proton discharges. The sustained photocatalytic activity of these complexes stems from their distinct ligand system, which includes phosphine and pyridine donors that aid in stabilizing the low oxidation states of the Ni center.

The regular octahedral CdS/K2Nb2O6 core-shell Z-Scheme heterojunction towards enhancing photocatalytic H2 evolution and degradation via synergism of carrier efficiency and light response

The regular octahedral CdS/K2Nb2O6 core-shell Z-Scheme heterojunction is synthesized via an approach of hydrothermal-chemical method. The CdS/K2Nb2O6 nano-heterojunction (CdS/KNO-3) exhibits arresting enhanced photocatalytic HER (∼634.39 μmol g−1 h−1)/degradation (∼0.05428 min−1) than the monomer K2Nb2O6 (∼27.8/14.4 folds) and CdS (∼20.3/10.0 folds), including a decent stability (average HER of ∼621.39 μmol∙g−1 h−1). It can be mainly attributed to the CdS/K2Nb2O6 Z-Scheme heterojunction with appropriate potential gradient can promote the interface carrier driving to optimize carrier efficiency, including increasing carrier transport, extending carrier lifetime and reducing recombination. Additionally, the octahedral core-shell nanostructure can provide numerous active sites for decreasing overpotential and promoting electron diffusion, while improving the solar efficiency (high solar response of CdS), including shorting carrier pathway for photocorrosion optimization and increasing structural stability.

Efficient photocatalytic H2 evolution over CuCo2S4 decorated ZnIn2S4 with S-scheme charge separation way

The construction of an S-scheme heterojunction can facilitate the separation and utilization of photogenerated charges, as well as reserve the reducing power of electrons to induce proton reduction for H2 evolution. In this study, CuCo2S4 nanoparticles and ZnIn2S4 nanoflowers were both synthesized via a hydrothermal method, and then CuCo2S4 was employed to decorate ZnIn2S4 to form CuCo2S4/ZnIn2S4 heterojunction through a simple physical solvent evaporation strategy. The experiment result shows that the rate of photocatalytic H2 evolution (rH2) over 10 wt% CuCo2S4/ZnIn2S4 can reach up to 20421.3 μmol g−1 h−1, which is 4.0 times that of ZnIn2S4 (5062.5 μmol g−1 h−1) and 144.6 times that of CuCo2S4 (141.2 μmol g−1 h−1). The improved activity results from the establishment of an S-scheme charge transfer way between CuCo2S4 and ZnIn2S4, which facilitates efficient charge separation while preserving active e− and h+. Besides, the formation of the heterojunction broadens the range of light absorption, promotes charge carrier generation, reduces charge transfer impedance, and increases electrochemically active surface area, these together lead to faster H2 evolution kinetics. The present study demonstrates the potential of bimetallic sulfides as a promising catalyst for construction ZnIn2S4-based photocatalysts for efficient solar conversion.

Enhanced interfacial electric field via sulfur vacancies modified ZnIn2S4-Vs@NiIn2S4 S-scheme photocatalysts for simultaneous H2 evolution and benzyl alcohol oxidation

Designing and developing efficient photocatalysts for H2 evolution and simultaneous oxidation of benzyl alcohol (BA) in aqueous environments provides a cutting-edge strategy for green synthesis. Nevertheless, the photocatalysts suffer from the low photoconversion efficiency because of the sluggish dynamics and repaid recombination of photogenerated charge carriers, which hindering their widespread applications. To address the limitation, a multifunctionnal sulfur vacancies (SVs) modified ZIS-Vs@NIS S-scheme heterojunction with a strong interfacial electric field effect was synthesized to use photocatalytic H2 production and BA oxidation, simultaneously. Experimental analysis supports that the synergistic effect of SVs and S-scheme heterojunction engineering result in a suitable energy band structure alignment and larger Fermi level potential difference. Those factors can realize effective charge transfer and separation, and enhance the photocatalytic performance. As anticipated, ZIS-Vs@NIS exhibited a superior photocatalytic performance with H2 and benzaldehyde (BAD) yields up to 168.1 and 146.1 μmol under the simulated solar-light irradiation for 1.0 h, respectively, which are approximately 13.3 and 11.8 times higher than pristine ZIS. Moreover, the photocatalytic H2 evolution coupled with BA oxidative dehydrogenation mechanism via S-scheme heterojunction over ZIS-Vs@NIS is also demonstrated in detail.

Nitrogen-oxygen defect engineering enhanced intrinsic electric field in CoFe2O4/g-C3N4 heterojunctions for photocatalytic tetracycline degradation and H2 evolution

A range of efficient g-C3N4/CoFe2O4 heterojunction with nitrogen deficiencies (NDs) and oxygen deficiencies (ODs) were successfully synthesized through doping-melting and hydrothermal methods. Nitrogen-oxygen defect engineering effectively enhanced the active sites on the catalyst surface and regulated the optical bandgap, band structure, and work function (Φ) of g-C3N4 and CoFe2O4, regulating the strength of the intrinsic electric field (IEF) and promoting the separation of photo-generated carriers at the heterojunction interface. Among the series of samples, CH-H2@CFO-A5 (properly oxalate-doped g-C3N4/CoFe2O4 heterojunctions treated with prolonged annealing) demonstrated remarkable optical properties due to its narrowest optical band gap, while the strongest IEF and redox potential make it has strong carrier dynamics and photocatalytic efficiency. Under visible light, the mineralization rate of tetracycline (TC) on CH-H2@CFO-A5 and the photocatalytic hydrogen production rate were 4.51 times and 2.72 times higher than that of unmodified CN-H0@CFO-A1, respectively. This study aimed to provide an efficient strategy for regulating the IEF within the heterojunction, by altering the Fermi level through multi-element defect engineering.

Highly dispersed g-C3N4 on one-dimensional W18O49/carbon nanofibers for constructing well-connected S-scheme heterojunctions with synchronous H2 evolution and pollutant degradation performance

Synchronous dual-functional photocatalytic reaction can simultaneously consume photogenerated electrons and holes, leading to redox reaction, which is a promising photocatalytic reaction system model. However, the severe recombination of photogenerated charge carriers in photocatalysts limits their photocatalytic performance. In this work, W18O49/C@g-C3N4 S-scheme heterojunctions nanofibers with core-shell structure were prepared through electrospinning combined with the vapor deposition method, for high-performance synchronous photocatalytic H2 evolution and pollutant degradation. The X-ray photoelectron spectroscopy and Mott-Schottky results demonstrated that the S-scheme heterojunctions effectively separate charges while maintaining high redox capacity. The UV-vis-NIR absorption spectra results revealed the LSPR effect in W18O49, which can generate “hot electrons”. The scanning electron microscope images showed that the unique core-shell structure independently consumes electrons and holes, thereby enhancing charge separation and accelerating carrier kinetics. Specifically, the synchronous H2 evolution and RhB degradation efficiency of W18O49/C@g-C3N4 nanofibers were approximately 5.60 and 3.51 times higher than that of W18O49/C, and 2.45 and 22.55 times higher than that of C@g-C3N4 nanofibers, respectively. Furthermore, the ultra-long one-dimensional network structure of W18O49/C@g-C3N4 nanofibers enables easy recycling after liquid reactions. This study presents a novel approach for customizing band structures and unique surface morphology to improve synchronous dual-functional photocatalytic activity.

Boosting photocatalytic H2 evolution in B-doped g-C3N4/O-doped g-C3N4 through synergistic band structure engineering and homojunction formation

Photocatalytic hydrogen production is a promising method to address the increasing energy demand and depletion of fossil fuels. Among various photocatalysts, g-C3N4 (CN) has attracted significant attention due to its favorable properties and tunable band structure. CN-based heterojunctions have been developed to enhance photocatalytic efficiency through improved charge separation via interfacial charge transfer. However, traditional heterojunctions formed between CN and other semiconductors often face challenges related to material compatibility and stability. In this work, we explored the formation of homojunctions, which involve identical semiconductors and offer superior charge separation and electron mobility due to perfect lattice matching. To further enhance individual oxidation and reduction capabilities, we employed band structure engineering through B doping and O doping. The homojunction between B-doped CN (BCN) and O-doped CN (OCN) was successfully synthesized using simple electrostatic self-assembly, resulting in significantly improved hydrogen production of 519.3 μmol g−1h−1 compared to BCN (34.7 μmol g−1h−1) and CN (167.2 μmol g−1h−1). This approach enhances visible light absorption, charge separation, and mobility, demonstrating the potential for developing advanced CN-based photocatalysts for various applications.

Carbon Doping Regulates Charge Transfer Paths via a Type-II to S-Scheme Transformation to Improve Photocatalytic Performance.

Designing S-scheme heterojunctions with enhanced interfacial interaction is an effective strategy for promoting the separation of photocarriers while maintaining strong photoredox capabilities. However, precisely tailoring the interfacial charge transport pathways between two contacted semiconductors remains a significant challenge due to the similar band alignment in type-II and S-scheme heterostructures. Herein, we report a facile and low-cost carbon doping strategy to smartly tune the charge transfer pathway via a type-II to S-scheme transformation for efficient photocatalytic H2 evolution and H2O2 synthesis. Density functional theory calculations combined with in situ XPS studies demonstrate that the Fermi level of MoO2 shifts from being higher than that of C3N4 to being lower after carbon doping, which drives the inversion of the internal electric field (IEF) direction between MoO2 and C3N4, thus enabling a transition from type-II MoO2/C3N4 heterojunctions to S-scheme C-MoO2/C3N4 heterojunctions. As a result, the optimal S-scheme C-MoO2/C3N4 heterojunctions exhibit a high H2 evolution rate of 16.2 mmol g-1 h-1 and a H2O2 production rate of 877 μmol g-1 h-1, notably surpassing those of the original C3N4 and type-II MoO2/C3N4 heterojunctions. This work provides valuable insights into the fabrication of C3N4 heterostructures and the control of electron migration pathways, thereby creating new possibilities for photocatalysis and optoelectronics applications.

Unraveling the Microstructure‐Property Relationship of Fe Single‐Atoms via Introducing Asymmetric P‐Coordination for Photocatalytic Hydrogen Evolution

AbstractThe local atomic environments of single‐atom photocatalysts play a decisive role in determining the solar‐to‐hydrogen energy conversion efficiency. However, controllably modulating the microstructure of single‐atom sites to enhance catalytic activity and deeply understanding the structure‐property relationship remain great challenges. Herein, electron‐rich P atoms are introduced to accurately regulate the local coordination environment and electronic configuration of Fe single atoms and construct a unique asymmetrical FeN3P2 motif into carbon nitride (FeN3P2‐CN) for significantly improving the photocatalytic H2 evolution activity and stability. Specifically, in the absence of noble metal cocatalyst and photosensitizer, the FeN3P2‐CN achieves a remarkable H2 evolution rate of 2668.5 µmol g−1 h−1 under visible light irradiation (λ > 420 nm), more than 105 times higher than that of unregulated FeN4 sample. Systematic characterizations and theoretical calculations unveil that the FeN3P2 single‐atom sites not only significantly broaden the photoabsorption region and facilitate the charge separation and interfacial transfer, but also efficiently promote adsorption and activation of H2O. This work paves a promising pathway to design novel single‐atom photocatalysts at the atomic level for achieving highly efficient water‐splitting performance.

Preparation of C-doped g-C3N4 by Co-polycondensation of melamine and sucrose for improved photocatalytic H2 evolution

g-C3N4, a well-known semiconductor is widely used for photocatalysis because of its renowned and special properties. It is a nonmetallic polymeric material that is abundant in sources and easy to prepare, making it an attractive choice for photocatalysis that responds to visible light. However, due to various intrinsic structural and chemical drawbacks, it is very far from further applications. Herein, we used sucrose to modify the physicochemical characteristics of ordinary g-C3N4 to prepare a carbon self-doped g-C3N4 (Cn-MA) material through co-polycondensation with melamine and applied it for hydrogen production. The characterization showed that the addition of sucrose resulted in a narrowed band gap, widened absorption range, enhanced photoresponse, and photogenerated charge carrier separation. Furthermore, the prepared material was applied for hydrogen production activity, which revealed that it has higher photocatalytic performance than pristine g-C3N4. The H2 production rate of the optimized material (C7.5-MA) was recorded as 7.3 times greater than that of pure g-C3N4. Through cycling tests, the stability of C7.5-MA was examined. The results showed that, even after four consecutive cycles, no apparent drop in its performance was observed. Additionally, here the mechanism of hydrogen production is also discussed.

Efficient Charge Carriers Separation and Transfer Driven by Interface Electric Field in FeS2@ZnIn2S4 Heterojunction Boost Hydrogen Evolution.

Photocatalytic H2 evolution technology is regarded as a promising and green route for the urgent requirement of efficient H2 production. At present, low efficiency is a major bottleneck that limits the practical application of photocatalytic H2 evolution. The construction of high-activity photocatalysts is highly crucial for achieving advanced hydrogen generation. Herein, a new S-scheme FeS2@ZnIn2S4 (FeS2@ZIS) heterostructure as the photocatalyst was developed for enhanced photocatalytic H2 evolution. Density function theory (DFT) calculation results strongly demonstrated that FeS2@ZIS generates a giant interface electric field (IEF), thus promoting the separation efficiency of photogenerated charge carriers for efficient visible-light-driven hydrogen evolution. At optimal conditions, the H2 production rate of the 8%FeS2@ZIS is 5.3 and 3.6 times higher than that of the pure FeS2 and ZIS, respectively. The experimental results further indicate that the close contact between FeS2 and ZIS promotes the formation of the S-scheme heterojunction, where the interfacial charge transfer achieves spatial separation of charge carriers. This further broadens the light absorption range of the FeS2@ZIS and improves the utilization rate of photogenerated charge carriers. This work thus offers new insights that the FeS2-based co-catalyst can enrich the research on S-scheme heterojunction photocatalysts and improve the transfer and separation efficiency of photogenerated carriers for photocatalytic hydrogen production.

In situ growth of ZnIn2S4 nanosheets on 2D NiFeS sheets from vulcanization of Ni–Fe LDH for enhancing photocatalytic hydrogen production

In this paper, 2-dimensional (2D) ZnIn2S4/NiFeS novel junctions were constructed through in-situ growing ZnIn2S4 nanosheets on 2D large NiFeS sheets with large specific area which were prepared from vulcanization of layer-structured Ni–Fe LDH by a solvent-thermal method. The rough and porous surface of FeNiS, as demonstrated by SEM pictures, endowed the heterojunction large interfacial area and more active sites for hydrogen evolution. Various tests indicate that the integration of a small amount of NiFeS in the heterojunction greatly improved carrier separation efficiency, migration rate, and surface H2 evolution activity, leading to the enhanced photocatalytic hydrogen production ability. Optimal 0.6%-NFS/ZIS composite shows the highest photocatalytic H2 evolution rate of 1506 μmol h−1 g−1, 2.4 times that of ZnIn2S4. This study provides a novel and cost-effective approach improving photocatalytic H2 evolution activity of sulfides in visible-light-driven water splitting.

The coexistence of highly dispersed Pt2+ and Pt0 co-catalysts on chemically oxidized g–C3N4 via metal-support interaction: The effect of reduction time on Pt species and hydrogen evolution of Pt/g-C3N4 photocatalysts

Platinum (Pt) cocatalyst greatly enhances the photoactivity of the graphitic carbon nitride (g-C3N4) photocatalyst for photocatalytic H2 evolution where the Pt properties are critical to determine the photocatalytic activity. In this study, highly dispersed Pt was successfully loaded onto chemically oxidized g–C3N4 (OCN) via a hydrogen reduction process over different reduction time. OCN photocatalysts containing highly dispersed Pt2+/Pt0 exhibited outstanding charge separation efficiency and photocatalytic performance. Symmetrical –CO groups on the OCN surface specifically interacted with atomic Pt2+, and the Pt2+ atoms were stably reduced to Pt0 atoms along with the generation of –OH groups over time. The coexistence of Pt0 and Pt2+ promoted superior photocatalytic performance because the photoinduced charge transfer was facilitated by the Pt0 atoms, which was evidenced by the DFT calculation and the EIS, PL, and photocurrent response results. Consequently, after the 24 h reduction, the highly stable and active Pt2+/Pt0 atoms were effectively distributed over OCN, resulting in the highest HER activity at 4091.3 µmol g−1 h−1.

Fabricating FeS2/Mn0.3Cd0.7S S-scheme heterojunction for enhanced photothermal-assisted photocatalytic H2 evolution under full-spectrum light

To effectively harness solar energy, the rational construction and development of full-spectrum photocatalysts has become an appealing challenge. In this study, a novel full-spectrum responsive FeS2/Mn0.3Cd0.7S (FS/MCS) S-scheme photocatalyst was obtained by attaching FeS2 nanoparticles with excellent photothermal properties on Mn0.3Cd0.7S nanorods. The photocatalytic hydrogen production rate of the optimal FS/MCS composite was 52.017 mmol·g−1·h−1 under full-spectrum irradiation, which was 3.88 times that of pure MCS. Based on the experimental results and density functional theory (DFT) calculations, the enhanced photoactivity of FS/MCS was attributed to the synergetic effects of photothermal and S-scheme heterojunction. The photothermal effect of FeS2 could convert the near infrared light to heat, which elevated the local temperature of photocatalyst particles, thereby promoting the photocatalytic reaction. Meanwhile, the S-scheme heterojunction between FeS2 and Mn0.3Cd0.7S accelerated the charge transfer and suppressed the recombination of electron-hole pairs, thereby enabling efficient charge separation while maintaining high redox potentials. This work offers a novel perspective on constructing a full-spectrum-driven photothermal-assisted photocatalytic H2 evolution system though the dual effects of photothermal and heterojunction.

Construction of two-dimensional heterojunctions based on metal-free semiconductor materials and Covalent Organic Frameworks for exceptional solar energy catalysis

Covalent organic frameworks (COFs) are newly developed crystalline substances that are garnering growing interest because of their ultra-high porosity, crystalline nature, and easy modified architecture, showing promise in the field of photocatalysis. However, it is difficult for pure COFs materials to achieve excellent photocatalytic hydrogen production due to their severe carrier recombination problems. To mitigate this crucial issue, establishing heterojunction is deemed an effective approach. Nonetheless, many of the metal-containing materials that have been used to construct heterojunctions with COFs own a number of drawbacks, including small specific surface area and rare active sites (for inorganic semiconductor materials), wider bandgaps and higher preparation costs (for MOFs). Therefore, it is necessary to choose metal-free materials that are easy to prepare. Red phosphorus (RP), as a semiconductor material without metal components, with suitable bandgap, moderate redox potential, relatively minimal toxicity, is affordable and readily available. Herein, a range of RP/TpPa-1-COF (RP/TP1C) composites have been successfully prepared through solvothermal method. The two-dimensional structure of the two materials causes strong interactions between the materials, and the construction of heterojunctions effectively inhibits the recombination of photogenic charge carrier. As a consequence, the 9% RP/TP1C composite, with the optimal photocatalytic ability, achieves a photocatalytic H2 evolution rate of 6.93 mmol g−1 h−1, demonstrating a 10.19-fold increase compared to that of bare RP and a 4.08-fold improvement over that of pure TP1C. This article offers a novel and innovative method for the advancement of efficient COFs-based photocatalysts.

Dual-Vacancy-Engineered ZnIn2S4 Nanosheets for Harnessing Low-Frequency Vibration Induced Piezoelectric Polarization Coupled with Static Dipole Field to Enhance Photocatalytic H2 Evolution.

This study investigates the impact of In- and S-vacancy concentrations on the photocatalytic activity of non-centrosymmetric zinc indium sulfide (ZIS) nanosheets for the hydrogen evolution reaction (HER). A positive correlation between the concentrations of dual In and S vacancies and the photocatalytic HER rate over ZIS nanosheets is observed. The piezoelectric polarization, stimulated by low-frequency vortex vibration to ensure the well-dispersion of ZIS nanosheets in solution, plays a crucial role in enhancing photocatalytic HER over the dual-vacancy engineered ZIS nanosheets. The piezoelectric characteristic of the defective ZIS nanosheets is confirmed through the piezopotential response measured using piezoelectric force microscopy. Piezophotocatalytic H2 evolution over the ZIS nanosheets is boosted under accelerated vortex vibrations. The research explores how vacancies alter ZIS's dipole moment and piezoelectric properties, thereby increasing electric potential gradient and improving charge-separation efficiency, through multi-scale simulations, including Density Functional Theory and Finite Element Analysis, and a machine-learning interatomic potential for defect identification. Increased In and S vacancies lead to higher electric potential gradients in ZIS along [100] and [010] directions, attributing to dipole moment and the piezoelectric effect. This research provides a comprehensive exploration of vacancy engineering in ZIS nanosheets, leveraging the piezopotential and dipole field to enhance photocatalytic performances.

A biomimetic upconversion nanoreactors for near-infrared driven H2 release to inhibit tauopathy in Alzheimer's disease therapy

Abnormal hyperphosphorylation of tau protein is a principal pathological hallmark in the onset of neurodegenerative disorders, such as Alzheimer's disease (AD), which can be induced by an excess of reactive oxygen species (ROS). As an antioxidant, hydrogen gas (H2) has the potential to mitigate AD by scavenging highly harmful ROS such as •OH. However, conventional administration methods of H2 face significant challenges in controlling H2 release on demand and fail to achieve effective accumulation at lesion sites. Herein, we report artificial nanoreactors that mimic natural photosynthesis to realize near-infrared (NIR) light-driven photocatalytic H2 evolution in situ. The nanoreactors are constructed by biocompatible crosslinked vesicles (CVs) encapsulating ascorbic acid and two photosensitizers, chlorophyll a (Chla) and indoline dye (Ind). In addition, platinum nanoparticles (Pt NPs) serve as photocatalysts and upconversion nanoparticles (UCNP) act as light-harvesting antennas in the nanoreacting system, and both attach to the surface of CVs. Under NIR irradiation, the nanoreactors release H2 in situ to scavenge local excess ROS and attenuate tau hyperphosphorylation in the AD mice model. Such NIR-triggered nanoreactors provide a proof-of-concept design for the great potential of hydrogen therapy against AD.

High-efficiency photocatalytic H2-evolution in water/seawater over a novel noble metal free Ni3C/Mn0.5Cd0.5S Schottky junction

Solar-powered seawater production of clean hydrogen fuel is highly prospective. In this work, Ni3C/Mn0.5Cd0.5S (NCMCS) Schottky junctions with excellent visible-light correspondence and photogenerated carrier separation properties are constructed using electrostatic attraction. The material achieves a hydrogen evolution rate of 6472.9 μmol h−1 g−1 in simulated seawater, which is 11 times higher than that of a single Mn0.5Cd0.5S (MCS). More attractively, the composite exhibits excellent hydrogen evolution rates in natural river water, groundwater and tap water, with significantly enhanced practical applicability. The underlying hydrogen evolution mechanism was extrapolated from a combination of experimental and theoretical calculations. The present work provides a low-cost and efficient hydrogen evolution photocatalyst for practical application, which can help promote the efficient conversion of solar-hydrogen energy.

Synergistic effects of carbon and nitrogen vacancies in carbon nitride for photocatalytic H2 production and tetracycline oxidation

Carbon nitride exhibits mediocre activity in photocatalytic environmental remediation and energy conversion due to its limited light absorption and sluggish charge transfer. Most studies have focused on structural engineering with either a single carbon or nitrogen defect, and insufficient attention has been paid to the effects of various defects within the bulk structure of carbon nitride on its photocatalytic activity. In this study, we prepared CN via thermal polymerization using different precursors, including melamine, 3-amino-1,2,4-triazole, 5-aminotetrazole, and a mixture of these compounds to explore the synergistic effects of carbon/nitrogen vacancies. All samples exhibited both carbon and nitrogen defects, which were correlated with the energy band gaps and sub-energy band levels, as well as photocatalytic activity for H2 evolution and tetracycline degradation. Among these samples, melamine-derived CN exhibited the fewest carbon/nitrogen defects and showed an apparent quantum yield of 7.6 % under light irradiation (λ = 420 nm) for photocatalytic H2 evolution. This sample was also used for tetracycline degradation and exhibited high activity and recyclability. A Pt-loaded melamine-derived CN sample was fabricated in a plate reactor for photocatalytic H2 evolution under sunlight. H2 evolution was correlated with sunlight intensity, revealing that our reactor holds promise for the potential large-scale production of H2 under daylight irradiation.