Highest Hydrogen Production Rate Research Articles

Enhanced hydrogen production through cracking of ammonia water using liquid plasma on titanate-based perovskite catalysts

In this study, a mass production of hydrogen was studied through cracking of ammonia water using liquid plasma. A new FexNi1-xTiO3 perovskite composite with significantly improved visible-light sensitivity was synthesized to further improve the photochemical reaction activity. It is applied to hydrogen production from the decomposition of ammonia water using liquid plasma. In this reaction, a large amount of hydrogen is produced with a small amount of nitrogen gas; moreover, oxygen is produced by liquid plasma discharge and no CO2 byproduct is produced. Titanate-based perovskite catalysts have also been used in decomposition reactions. Titanate-based perovskite catalysts exhibiting high rates of hydrogen production during decomposition were obtained for the plasma and photocatalytic decomposition of aqueous ammonia. FexNi1-xTiO3, which is a newly synthesized ABTiO3-type titanate, showed a higher rate of hydrogen production (approximately 140 L/(g·h)) than other titanate-based perovskites. Furthermore, the FexNi1-xTiO3 exhibited the highest sensitivity to UV and visible light. Its high photosensitivity helped improve the photocatalytic activity in the decomposition of ammonia in water using plasma.

Synchronized sulfur resource recovery and hydrogen production via a self-powered system based on multifunctional Co3S4 catalyst

Self-driven recycling of sulfur-containing wastewater and hydrogen production is a novel concept that integrates environmental protection and new energy development. In this study, we designed for the first time a Zn-air battery self-driven coupling system for the hydrogen evolution reaction (HER), sulfur oxidation reaction (SOR) and developed a trifunctional catalyst suitable for this system capable of HER, SOR, and oxygen reduction reaction (ORR). By synthesizing cobalt sulfide (Co3S4) in situ on nickel foam (NF), we obtained Co3S4/NF monolithic catalyst. It only requires 0.312 V and 0.244 V in SOR and HER, respectively, at 100 mA cm−2. Based on this achievement, the SOR||HER coupled electrolysis system was assembled, which achieved 0.69 V at 100 mA cm−2. Furthermore, the Zn-air battery (using Co3S4 as ORR catalyst) could spontaneously drive the SOR||HER system to achieve high-rate hydrogen production. These findings provide promising opportunities for zero-energy consumption H2 production and recycling of sulfur-containing wastewater.

Hydrogen sulfide methane reforming: A kinetic modeling and techno-economic analysis study

Hydrogen sulfide (H2S) methane (CH4) reforming (H2SMR) is a promising process for sustainable energy production from conventional fuels, offering triple benefits for generating clean hydrogen (H2), consuming toxic H2S, and producing an economically valuable by-product carbon disulfide (CS2). In this work, we studied the optimal operating conditions and assessed the economic feasibility of the non-catalytic H2SMR process, employing a combination of kinetic modeling, process modeling, and techno-economic analysis. Plug flow reactor simulations were performed with our newly developed mechanism to shed light on the optimal operating conditions. It was concluded that a H2S/CH4 molar feed ratio of 2 results in the highest hydrogen production rate, and a feed ratio of 1–2 and a temperature of 1100–1300 °C are needed to maximize the CS2 production rate. However, feed ratios higher than 2 increase the conversion rate of CH4 and therefore benefit the purity of the H2 product. Comparing the cases for a feed ratio of 2 at 1300 °C and a feed ratio of 9 at 1200 °C, the cost is significantly higher for the feed ratio of 9, mainly attributed to the higher electricity cost for higher inlet flow rate and H2S recycling, as well as the cost for the additional steam required during the preheating process. The cost of hydrogen production by H2SMR process could be as low as $1.47/kgH2 for a feed ratio of 2 and solar PV as an energy source, which is more competitive than a cost of $1.97/kgH2 for the steam methane reforming process. Furthermore, since CS2 is a valuable by-product, the higher amount of CS2 formed at a feed ratio of 2 becomes the main source of revenue, which completely covers the cost of hydrogen production. This study demonstrates the huge potential of H2SMR process as a clean and economic-competitive way to produce hydrogen.

Tuning Electrons Migration of Dual S Defects Mediated MoS2-x/ZnIn2S4-x Toward Highly Efficient Photocatalytic Hydrogen Production.

Photocatalytic hydrogen production is a prevalent method for hydrogen synthesis. However, high recombination rate of photogenerated carriers and high activation energy barrier of H remain persistent challenge. Here, the two-step hydrothermal method is utilized to prepare dual S-defect mediated catalyst molybdenum sulfide/zinc indium sulfide (MSv/ZISv), which has high hydrogen production rate of 8.83 mmolg-1h-1 under simulated sunlight. The achieved rate is 21.91 times higher than pure ZnIn2S4 substrate. Defects in ZIS within MSv/ZISv modify the primitive electronic structure by creating defect state that retaining good reducing power, leading to the rapid separation of electron-hole pairs and the generation of additional photogenerated carriers. The internal electric field further enhances the migration toward to cocatalyst. Simultaneously, the defects introduced on the MoS2 cause electron rearrangement, leading to electron clustering on both S vacancies and edge S. Thereby MSv/ZISv exhibits the lowest activation energy barrier and |ΔGH*|. This work explores the division of synergies between different types of S defects, providing new insights into the coupling of defect engineering.

Interfacial charge transfer complexes between ZnO and benzene derivatives: Characterization and photocatalytic hydrogen production

The interfacial charge transfer (ICT) complex formation is a simple procedure to bring optical absorption of wide-bandgap oxide materials in the visible spectral range, crucial for enhancing their use in photo-driven reactions. The optical absorption of the prepared ICT complexes between ZnO and five different colorless benzene derivatives is red-shifted compared to pristine ZnO nanopowder. The density functional theory (DFT) calculations provided realistic energy level alignment in hybrid systems. Also, the DFT-calculated infrared spectra support the binding structures derived based on experimental measurements of free and adsorbed ligands onto ZnO surfaces. The photocatalytic performance of prepared hybrids was evaluated using photocatalytic hydrogen generation in the water-splitting reaction. The ZnO nanopowders modified with catechol and caffeic acid have over 50% higher hydrogen production rate than pristine ZnO, displaying steady hydrogen production under long-run working conditions.

Design of a novel tubular membrane reactor with a middle annular injector for enhancement of dry reforming towards high hydrogen purity: CFD analysis

This study introduces a novel design of a tubular porous membrane catalytic reactor (TPMCR) with a middle annular injector, which aims to improve the performance of a dry reforming of methane (DRM) process. A computational fluid dynamics (CFD) model is developed for a fundamental configuration and subsequently verified using experimental data. The validated CFD model is utilized to examine the influence of different parameters, such as feed composition, inlet gas temperature and pressure, and injection rate, on the reactor performance. The study findings reveal that the introduction of a secondary gas during the injection process has the potential to regulate the process and positively affect the production rates of hydrogen and carbon monoxide. The optimal inlet temperature to attain the highest rate of hydrogen production is determined to be 900 K. The hydrogen selectivity is found to increase from 0.96 to 1.60 with the injection of pure steam when the injection rate is increased from 50 to 500 kg/(m2.s). In addition, the carbon monoxide selectivity is decreased from 6.30 to 2.67. The implementation of a middle annular injector within the proposed TPMCR design offers the potential for enhancing the efficiency and sustainability of chemical reactors. Consequently, the introduced modification leads to more efficient and environmentally friendly chemical processes, specifically in the realms of syngas and hydrogen production through the DRM process, resulting in improved purity levels.

Reinforcement of methanol catalytic reforming for hydrogen production through Ru-based carbon-coated CeO2 catalyst

Methanol steam reforming for hydrogen production is a highly promising energy technology, due to the high hydrogen intensity of methanol and the appendant hydrogen capture from water. In order to reinforce the hydrogen yield in methanol steam reforming reaction, a series of Ru-based carbon-coated CeO2 catalysts were prepared in this work, using glucose, cellulose and activated carbon as different carbon sources via a hydrothermal method. The results showed that the Ru/CG-CeO2 (glucose) catalyst exhibited a superior catalytic performance at the reaction temperature of 400 °C, with a higher hydrogen production rate (0.276 mol/h) than Ru/CC-CeO2 (cellulose, 0.230 mol/h) and Ru/CA-CeO2 (activated carbon, 0.253 mol/h) catalysts. This was attributed to the synergistic effect between CeO2 and carbon, where the carbon layer formed by glucose enhanced the interaction between the active component and the CeO2 support, which also facilitated the electron transfer effects and resulted in a large amount of oxygen vacancies for Ru/CG-CeO2. This led to a strong adsorption capacity for CO and oxygen-containing species derived from the substrate, thereby improving hydrogen production. Additionally, the catalyst stability and the resistance to carbon deposition were evaluated for all the three catalysts, and Ru/CG-CeO2 catalyst also demonstrated a superior stability and anti-carbon deposition capability.

Evaluation of the effect of increasing the organic load in the thermophilic co-fermentation of sugarcane industry by-products on hydrogen, ethanol and lactic acid generation

The effects of increased organic loading rate (OLR) on H2 production and soluble metabolites in a thermophilic anaerobic fluidized bed reactor (AFBR-AT) at 55 °C were evaluated by the fermentation of vinasse and molasses from sugarcane (at a ratio of 1:1). The OLR varied between 30 and 135 kg COD.m−3.d−1, while the hydraulic retention time (HRT) was fixed at 4 h, and the initial co-substrate concentration varied between 5 and 22.5 g COD.L−1. The thermophilic acidogenic reactor showed a maximum hydrogen yield (HY) (2.49 mmol H2.g−1CODapp) at an OLR of 30 kg COD.m−3.d−1 and a higher hydrogen production rate (HPR) (2.8 L H2.L−1.d−1) at an OLR of 45 kg COD.m−3.d−1. Increasing the OLR negatively influenced H2 production. The results showed an increase in ethanol (EtOH) concentrations of up to 47.3 times and lactic acid (HLa) concentrations of up to 15.2 times when comparing OLRs of 30 and 135 kg COD.m−3.d−1, indicating changes in metabolic pathways for acid formation at organic loads ≥90 kg COD.m−3.d−1. Thermoanaerobacterium was the bacteria with higher relative abundance and was directly involved in H2 production, while Lactobacillus was mainly involved in HLa production in higher OLR, decreasing H2 production instead. Besides that, higher OLRs were favorable for sulfidogenesis and the development of sulfate-reducing bacteria, such as Desulfobacterota, due to the higher COD/sulfate ratio in OLR 135 kg COD.m−3.d−1. According to the metabolic inference in this condition, the enzyme activity of sulfite reductase and sulfite dehydrogenase may have occurred, consuming H+, thereby reducing H2 production.

Efficient Low-temperature Hydrogen Production by Electrochemical-assisted Methanol Steam Reforming.

Methanol steam reforming (MSR) provides an alternative way for efficient production and safe transportation of hydrogen but requires harsh conditions and complicated purification processes. In this work, an efficient electrochemical-assisted MSR reaction for pure H2 production at lower temperature (~140 °C) is developed by coupling the electrocatalysis reaction into the MSR in a polymer electrolyte membrane electrolysis reactor. By electrochemically assisted, the two critical steps including the methanol dehydrogenation and water-gas shift reaction are accelerated, which is attributed to decreasing the methanol dehydrogenation energy and promoting the dissociation of H2 O to OH* by the applied potential. Furthermore, the reduced H2 partial pressure by the hydrogen oxidation and reduction process further promotes MSR. The combination of these advantages not only efficiently decreases the MSR temperature but also achieves the high rate of hydrogen production of 505 mmol H2 g Pt -1 h-1 with exceptionally high H2 selectivity (99 %) at 180 °C and a low voltage (0.4 V), and the productivity is about 30-fold than that of traditional MSR. This study opens up a new avenue to design novel electrolysis cells for hydrogen production.

Efficient Low‐temperature Hydrogen Production by Electrochemical‐assisted Methanol Steam Reforming

AbstractMethanol steam reforming (MSR) provides an alternative way for efficient production and safe transportation of hydrogen but requires harsh conditions and complicated purification processes. In this work, an efficient electrochemical‐assisted MSR reaction for pure H2 production at lower temperature (~140 °C) is developed by coupling the electrocatalysis reaction into the MSR in a polymer electrolyte membrane electrolysis reactor. By electrochemically assisted, the two critical steps including the methanol dehydrogenation and water‐gas shift reaction are accelerated, which is attributed to decreasing the methanol dehydrogenation energy and promoting the dissociation of H2O to OH* by the applied potential. Furthermore, the reduced H2 partial pressure by the hydrogen oxidation and reduction process further promotes MSR. The combination of these advantages not only efficiently decreases the MSR temperature but also achieves the high rate of hydrogen production of 505 mmol H2 g Pt−1 h−1 with exceptionally high H2 selectivity (99 %) at 180 °C and a low voltage (0.4 V), and the productivity is about 30‐fold than that of traditional MSR. This study opens up a new avenue to design novel electrolysis cells for hydrogen production.

Construction of CeO2/ZnTCPP heterojunction with enhanced photocatalytic hydrogen production performance

In this work, a two-step solvothermal method was used to design CeO2/ZnTCPP composites for photocatalytic hydrogen evolution. Systematic characterization including morphological, structural, optical and electrochemical measurements revealed a correlation between the sample structure and photocatalytic activity. Compared with pure CeO2 and ZnTCPP, the optimized CeO2/ZnTCPP photocatalyst has good hydrogen production performance (1314.6 μmol g-1h-1). At the same time, the catalyst can still maintain a high hydrogen production rate (1162.7 µmol g-1h-1) under visible light. The experimental results showed that the CeO2/ZnTCPP composites have high carrier separation efficiency, which is attributed to the formation of a type-II heterojunction in the structure between the CeO2 and ZnTCPP.

Dodecahedral hollow multi-shelled Co3O4/Ag:ZnIn2S4 photocatalyst for enhancing solar energy utilization efficiency.

Employing semiconductor photocatalysts featuring a hollow multi-shelled (HoMs) structure to establish a heterojunction is an effective approach to addressing the issues of low light energy utilization and severe recombination of photogenerated charge carriers. To take advantage of these key factors in semiconductor photocatalysis, here, a dodecahedral HoMs Co3O4/Ag:ZnIn2S4 photocatalyst (denoted as Co3O4/AZIS) was firstly synthesized by coupling Ag+-doped ZnIn2S4 (AZIS) nanosheets with dodecahedral HoMs Co3O4. The unique HoMs structure of the photocatalyst can not only effectively promote the separation and transfer of photo-induced charge, but also improve the utilization rate of visible light, exposing rich active sites for the photocatalytic redox reaction. The photocatalytic experiment results showed that the Co3O4/90.0 wt% AZIS photocatalyst has a high hydrogen (H2) production rate (695.0 μmol h-1 g-1) and high methyl orange (MO) degradation rate (0.4243 min-1). This work provides a feasible strategy for the development of HoMs heterojunction photocatalysts with enhanced H2 production and degradation properties of organic dyes.

A rationally designed 3DTiO2@CdZnS heterojunction photocatalyst for effectively enhanced visible-light-driven hydrogen evolution.

Hydrogen production with higher efficiency and lower cost is of great significance for the sustainable development of energy. Zinc cadmium sulfide (CZS) is gaining more attention owing to its excellent photocatalytic properties. However, its development is greatly limited due to photogenerated charge recombination. In this work, an innovative design with a unique 3D morphology was introduced by integrating 3DTiO2 into CZS to form a novel 3DTiO2/CZS heterojunction photocatalyst. As a result, the optimized composite achieved a very high hydrogen production rate of 75.38 mmol h-1 g-1 under visible light, which is 2.4 times higher than that of the original CZS. It can also be greatly demonstrated through photoelectrochemical tests that this unique 3D morphology contributes to the effective separation of electrons and holes, thus dramatically improving the photocatalytic activity of 3DTiO2/CZS composites. The 3DTiO2/CZS composite has a rational energy band structure, which makes it more favorable for the hydrogen precipitation reaction. It is believed that such a modification strategy based on 3DTiO2 can be applied to other similar photocatalysts as well for boosting hydrogen evolution.

Prefeasibility analysis of biomass gasification and electrolysis for hydrogen production

Hydrogen is a key energy vector to accomplishing energy transition and decarbonization goals proposed in the transport and industrial sectors worldwide. In recent years, research has focused on analyzing, designing, and optimizing hydrogen production, searching to improve economic prefeasibility with minimal emissions of polluting gases. Therefore, the techno-economic analysis of hydrogen production by electrolytic and gasification processes becomes relevant since these processes could compete commercially with industrial technologies such as SMR - Steam methane reforming. This work aims to analyze hydrogen production in stand-alone processes and energy-driven biorefineries. The gasification and electrolysis technologies were evaluated experimentally, and the yields obtained were input data for scaling up the processes through simulation tools. Biomass gasification is more cost-effective than electrolytic schemes since the hydrogen production costs were 4.57 USD/kg and 8.30 USD/kg at an annual production rate of 491.6 tons and 38.96 tons, respectively. Instead, the electrolysis process feasibility is strongly influenced by the recycled water rate and the electricity cost. A sensitivity analysis was performed to evaluate the temperature, pressure, and current density variability on the hydrogen production rate. The increase in pressure and current density induces parasitic currents while the temperature increases hydrogen production. Although higher hydrogen production rates from gasification, the syngas composition decreases the possibility of being implemented in applications where purity is critical.

Initial Degradation Issues in AEMWE and the Importance of Catalyst/Ionomer Binding

With the recent development of highly alkaline stable anion exchange membranes (AEMs) and ionomers (AEIs), anion exchange membrane water electrolyzer (AEMWE) has garnered attention due to its ability to achieve high hydrogen production rate at a low cost. The performance of AEMWE is determined by the anode catalyst layer, which can be made up of either a mixture of metal nanoparticles and polymer binders or a single metal. Although the integral metal has high mechanical properties, its performance is limited due to low electrochemical surface area and difficulties in mixing with binders, which makes it unsuitable for use in pure water. Catalyst layers made up of a combination of metal nanoparticles and polymeric binders can achieve high performance with a large surface area, but they often have low durability due to detachment of the anode catalyst layer from the porous transport layer substrate during water electrolysis. To prevent this, the anode catalyst layer must have high physical stiffness and it can be achieved by the strong bonding between the metal nanoparticles and the ionomer binder. This presentation investigates the phenomenon of initial performance degradation in AEMWE with an anode catalyst layer composed of metal nanoparticles, highlights the significance of the physical stiffness of the anode catalyst layer, and proposes that the issue can be resolved by introducing a polymer binder with high adhesion between the metal nanoparticles and the ionomer binder.

Low-Voltage Hydrogen Production via Hydrogen Peroxide Oxidation Facilitated by Oxo Ligand Axially Coordinated to Cobalt in Phthalocyanine Moiety

The global energy sector is shifting from fossil-based systems of energy production and consumption to renewable-based ones like wind and solar energy. Hydrogen has emerged as one of the energy carriers for the renewable-based economy, storing electrical energy generated from the renewables and being used as a fuel to generate power. Water electrolysis, powered by renewable energies, is one of the most feasible green hydrogen production technologies. At least 1.23 V and typically > 2 V is required between hydrogen and oxygen evolution reactions (HER and OER) for splitting water. OER is notorious for its slow kinetics so that the OER determines hydrogen production rate. Therefore, it has been emphasized to develop high-performance and low-cost OER electrocatalysts for reducing overpotentials required for electrolyzing water. Even if up-to-date upgraded electrocatalysts have decreased the kinetic overpotentials, it is clearly evident that it is impossible to split water molecules at the cell voltage less than 1.23 V. To decrease the potential required for water electrolysis, water oxidation reaction to drive OER was suggested to be replaced by oxidation of organic molecules or nitrogen hydrides such as formic acid and hydrazine. However, even if the more negative E o of the organic molecules allowed the open-circuit potential difference between cathodic and anodic processes to be reduced, it sounds self-contradictory to employ carbon-based organic molecules and therefore produce carbon dioxide for producing green hydrogen.Suggesting hydrogen peroxide as an electrolysis medium for hydrogen production and therefore as a hydrogen carrier, in this work, we present a cobalt phthalocyanine having electron-poor CoN4 (+δ) in its phthalocyanine moiety as an electrocatalyst for hydrogen peroxide oxidation reaction (HPOR), demonstrating that the electrocatalyst guaranteed high hydrogen production rate by hydrogen peroxide splitting. The electron deficiency of cobalt allowed CoN4 to have the highly HPOR-active monovalent oxidation state and facilitate HPOR at small overpotentials range around the onset potential. The strong interaction between the electron-deficient cobalt and oxygen of peroxide adsorbates in Co-OOH- encouraged an axially coordinated cobalt oxo complex (O=CoN4) to form, the O=CoN4 facilitating the HPOR efficiently at high overpotentials. Low-voltage oxygen evolution reaction (OER) guaranteeing low-voltage hydrogen production was successfully demonstrated in the presence of the metal-oxo complex having electron-deficient CoN4. Hydrogen production by 391 mA cm-2 at 1 V and 870 mA cm-2 at 1.5 V was obtained.Also, we evaluated the techno-economic benefit of hydrogen peroxide as a hydrogen carrier by comparing hydrogen peroxide with other hydrogen carriers. Here, even though water (H2O) can be considered as a carrier, about 61 kWh/kg of energy is required for converting transported H2O to H2 again. Thus, in this case, if renewable energy can be supplied from the demand site, H2 can be produced directly on-site from the demand site without having to transport the H2 produced from another renewable energy complex. If renewable power cannot be supplied from the demand site, all the required energy for water electrolysis should be supplied with existing fossil fuel-based energy, it is like losing the eco-friendly significance of H2 energy, and considering energy consumption, using other carriers will be more economical and environmental. In this situation, H2O2 can act as a hydrogen carrier as a hydrogen/oxygen simultaneous receptor. When generated hydrogen is stored and transported, high cost arises. To lower the cost, many countries are paying attention to LOHC (=liquid organic hydrogen carrier) and ammonia which are materials to storage hydrogen energy. For LOHC, methylcyclohexane 6.1 wt.% and 47 kg H2/m3, dibenzyltoluene 6.2 wt.% and 57 kg H2/m3, ethylcarbazole 5.8 wt. % and 57 kg H2/m3, with a hydrogen storage capacity of 47 - 57 kg H2/m3. For ammonia, it has a hydrogen storage capacity of 17.6 wt. %, and 108 kg H2/m3. In the case of H2O2, it has 5.9 wt.% and 85.3 kg H2/m3, which belongs to the high hydrogen storage capacity compared to other hydrogen storage materials. To evaluate the economic analysis, we conducted to identify that H2O2 can be utilized for green H2 supply by comparing diverse hydrogen storage and transportation pathways. Furthermore, the scenario analysis was performed for CGH2, LH2, NH3, toluene-based LOHC, and H2O2. Figure 1

Kinetic Study of the Aluminum–water Reaction Using NaOH/NaAlO2 Catalyst for Hydrogen Production from Aluminum Cans Waste

The presence of oxide layers covering the surface of aluminum is known to impede the hydrogen production reaction. These oxide layers can be broken by adding catalysts and increasing the aluminum-water reaction temperature. Common catalysts used are alkaline catalysts that are capable of achieving high hydrogen production rates in a short time at lower temperatures, while intermediate temperatures of above 50 °C can accelerate the hydration reaction of the oxide layer. Herein, the mixture of NaOH and NaAlO2 catalysts was employed to attain a stable NaAlO2 solution and continuous reaction of NaOH and aluminum. This research analyzes the influence of temperature between 32 and 80 °C on the aluminum, 0.3 M NaOH and 0.001 M NaAlO2 catalysts solution at atmospheric pressure. All solutions produces a similar hydrogen yields and rate. Solutions containing NaAlO2 indicate reverse reaction that surpressing the Al(OH)3 precipitation. Residue from the reaction is investigated using X-ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscope (SEM). The volume of hydrogen produced is evaluated using a mathematical mass reduction and shrinking core model. The rate of hydrogen production depends largely on the aqueous solution's temperature, with an activation energy of 47.4 kJ/mol. Based on the findings, it is readily apparent that the reaction only produced gibbsite and bayerite, with gibbsite and bayerite being dominant at 32–70 °C and 80 °C, respectively. The mass reduction model fits well with the present results with only an average 5.1 mL deviation, whereas the shrinking core model generally tends to result in underestimated values with an average deviation of 23.9 mL. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A novel graphitic carbon nitride photocatalyst with ultramicro amounts of intramolecular donor-acceptor structures for excellent photocatalytic hydrogen production

In this study, facile supramolecular thermal polymerization was employed for an attempt to modify graphitic carbon nitride (g-C3N4) using ultramicro amounts of diphenylamino-4-benzaldehyde as the dopant, and melamine and cyanuric chloride as the raw materials. The reaction of aldehyde-amine achieved diphenylamino-4-benzaldehyde grafting onto the edge of the heptazine ring of g-C3N4, resulting in the formation of a novel g-C3N4 with intramolecular twisted donor–acceptor (D-A) structures known as CN-Dxmg. It was confirmed that addition of 2 mg (0.67 wt‰) of diphenylamine-4-benzaldehyde as the donor regulated the energy level distribution of CN-D2mg, and as-obtained intramolecular D-A structures can promote the photogenerated carrier separation and migration of CN-D2mg through a directional channel for electron transfer from diphenylamine-4-benzaldehyde to heptazine. The results indicate that CN-D2mg photocatalyst has a high hydrogen production rate of 14581.1 μmol·h−1·g−1 at 420 nm under visible light irradiation, which is 1.6 times higher than that of pristine g-C3N4. The study presents an effective approach for large-scale applications involving g-C3N4 photocatalyst in clean energy production.

The construction of CdxZn1-xS-based photocatalysts for enhanced hydrogen generation

CdxZn1-xS (x=0~1) solid solution photocatalyst with different morphologies was synthesized by solvothermal method using ethylenediamine as solvent. The light absorption of the photocatalyst was varied by changing the morphology and electronic band structure to allow strong visible light response for hydrogen generation. The results showed that the optimum sample Cd0.5Zn0.5S showed a high hydrogen production rate of 2531.3 μmol·g-1 ·h-1 with lactic acid as sacrificial agent. Loading with NiS by solvothermal method further improves the hydrogen production performance. The photocatalytic hydrogen evolution rate of NiS/Cd0.5Zn0.5S is 4547.5 μmol·g-1 ·h-1 , which is 1.80 times that of pure Cd0.5Zn0.5S. The mechanism of hydrogen production by NiS/Cd0.5Zn0.5S is also discussed.

Green synthesis of Ag2S nanoparticle from sweet cherry on ultrasound-assisted prepared NiMoO4/g-C3N4 nanocomposite for photocatalytic H2 production

Photocatalytic hydrogen production from water is important in terms of producing various photocatalysts because it is an environmentally friendly, clean, and renewable energy source. In this work, we reported that NiMoO4/g-C3N4/Ag2S were obtained through the green synthesis method using sweet cherry. The structural, morphological, and optical features of synthesized photocatalysts were evaluated by XRD, FTIR, UV–visible DRS, SEM, TEM, and XPS. In addition, the electrochemical measurements were investigated. The hydrogen production yields of all photocatalysts were determined by gas chromatography with a thermal conductive detector for a total reaction time of 4 h. The resulting NiMoO4/g-C3N4/Ag2S has the highest hydrogen production rate with 2040.2 μmol g−1 h−1 compared to NiMoO4, g-C3N4, Ag2S and NiMoO4/g-C3N4. In this catalyst design system, in the entity of an electric field created by the S-scheme heterostructure of NiMoO4/g-C3N4/Ag2S, influential directional migration of photocarriers is acquired, and recombination of useful charge carriers is avoided. This work highlights the utilization of green synthesis of ternary nanocomposite from sweet cherry for photocatalytic hydrogen production.