Highest H2 Production Rate Research Articles

Extraordinary Catalytic Performance of Nickel Half‐Metal Clusters for Light‐Driven Dry Reforming of Methane

AbstractGlobal warming and the energy shortage due to the burning of fossil fuels are two major challenges. A strategy of light‐driven catalytic dry reforming of methane (DRM) using inexhaustible solar energy has provided an effective approach to tackle these challenges. Loaded metallic Ni nanoparticles have been identified as promising catalysts as alternatives to noble metals for DRM. However, they suffer from quick deactivation caused by severe coking due to thermodynamically inevitable side‐reactions. Herein, a unique nickel half‐metal catalyst of monolayer nickel clusters stabilized by alumina is reported, with 100% atomic utilization efficiency and extraordinary catalytic performance for light‐driven DRM, dramatically different from its counterpart of conventional metallic Ni nanoparticles. It has extremely high specific H2 and CO production rates of 8572.96 and 9614.26 mmol min−1 gNi−1, more than one order of magnitude higher than those of Ni nanoparticles. No detectable coke is formed due to the alteration of kinetic processes for DRM, resulting in the inhibition of coke deposition. It is discovered that light not only significantly enhances catalytic activity, but also enables quick thermocatalytic deactivation to be durable due to the oxidation of carbon species and the desorption of strongly adsorbed CO2 and CO being dramatically promoted by light.

Zn0.1Cd0.9S/NiS heterojunction photocatalysts for enhanced H2 production and glucose conversion

The well-designed photocatalyst is a reasonable strategy to realize the photocatalytic H2-production and biomass conversion. In this work, the noble-metal-free Zn0.1Cd0.9S/NiS (SNS) composite was successfully prepared by in-situ chemical bath deposition of NiS nanoparticles on Zn0.1Cd0.9S (ZCS) nanorods surface for photocatalytic H2-production using glucose as electron donors for effective utilization of holes. Our results show that the synergistic effect of NiS and ZCS largely improves the absorption and utilization of light, and the photogenerated electrons transfer from NiS to ZCS to effectively separate the photogenerated carriers for the enhanced photocatalytic H2-production as the one-dimensional nanorods is conducive to the transmission of photogenerated carriers. The optimized catalyst (SNS20) has the highest H2 production rate (12.77 mmol·g−1·h−1), which is 6.7 times that of pure ZCS nanorods. In particular, its apparent quantum efficiency (AQE) at 350 nm reaches 12.74%. The glucose conversion increases from 25.7% to 49.9% and lactic acid selectivity reaches 95%. During three cycles, the SNS20 shows the stable H2-production rate, which remains 12 mmol·g−1·h−1 after three cycles. And the glucose conversion still remains above 40%. This work provides a reasonable strategy for designing heterojunction photocatalyst to improve the performance for the synergy of photocatalytic H2-production and biomass conversion.

Insight into synergistic effect of Ti3C2 MXene and MoS2 on anti-photocorrosion and photocatalytic of CdS for hydrogen production

Facing the increasingly serious issues of energy crisis and environmental pollution, it is vital to develop efficient and durable photocatalysis systems for hydrogen (H2) production from water splitting. However, for the famous CdS-based systems, the bottleneck of poor efficiency and low stability arisen from photocorrosion has not been broken through yet. In this study, a ternary composite of CdS, MoS2 and Ti3C2 MXene with intimately contact interfaces was successfully constructed via an in situ growth method, which exhibited reinforced photocatalytic H2-production activity and increased photocorrosion resistant capability. Both of experimental characterizations and density functional theory (DFT) calculations well proved that the photogenerated holes and electrons of CdS timely migrated to Ti3C2 and MoS2, respectively. As a consequence, the optimal sample displayed a high H2 production rate of 14.88 mmol·h−1·g−1 with a lifetime of up to 78 h, and the component and structure of the composite were kept intact during the photocatalysis reaction. This work highlights the synergistic effect of the Ti3C2 MXene and MoS2 as redox dual cocatalysts on the promoted photocatalytic performance and durability of CdS, which can be anticipated to significantly enhance the commercial availability of CdS and even boost its incorporation into industrial applications.

Cocatalyst Engineering with Robust Tunable Carbon‐Encapsulated Mo‐Rich Mo/Mo2C Heterostructure Nanoparticle for Efficient Photocatalytic Hydrogen Evolution

AbstractCocatalyst engineering with non‐noble metal nanomaterials can play a vital role in low‐cost, sustainable, and large‐scale photocatalytic hydrogen production. This research adopts slow carburization and simultaneous hydrocarbon reduction to synthesize carbon‐encapsulated Mo/Mo2C heterostructure nanoparticles, namely Mo/Mo2C@C cocatalyst. Experimental and theoretical investigations indicate that the Mo/Mo2C@C cocatalysts have a nearly ideal hydrogen‐adsorption free energy (ΔGH*), which results in the accelerated HER kinetics. As such, the cocatalysts are immobilized onto organic polymer semiconductor g‐C3N4 and inorganic semiconductor CdS, resulting in Mo/Mo2C@C/g‐C3N4 and Mo/Mo2C@C/CdS catalysts, respectively. In photocatalytic hydrogen evolution application under visible light, the Mo/Mo2C@C with g‐C3N4 and CdS can form the Schottky junctions via appropriate band alignment, greatly suppressing the recombination of photoinduced electron‐hole pairs. The surface carbon layer as the conducting scaffolds and Mo metal facilitates electron transfer and electron‐hole separation, favoring structural stability and offering more reaction sites and interfaces as electron mediators. As a result, these catalysts exhibit high H2 production rates of 2.7 mmol h−1 g−1 in basic solution and 98.2 mmol h−1 g−1 in acidic solution, respectively, which is significantly higher than that of the bench‐mark Pt‐containing catalyst. The proposed cocatalyst engineering approach is promising in developing efficient non‐noble metal cocatalysts for rapid hydrogen production.

Photocatalytic H2 generation from ethanol and glucose aqueous solutions by PtOx/TiO2 composites

A new straightforward protocol for the deposition of the platinum oxide (PtO–PtO2) particles onto the TiO2 semiconductor via controllable hydrolysis of the sulfuric acid solution of Pt(IV) hydroxide was developed. The developed approach represents a simple and “green” way to prepare the supported Adams-type catalysts. In the constructed composites (PtO2·xH2O/TiO2) the Pt ionic species (hydrated PtO and PtO2 nanoparticles) weakly interact with the titania surface, but under heating the Pt–O–Ti bonds are established, resulting in the stabilization of the Pt(II) ionic state. This state dominates in the obtained catalysts PtOx/TiO2 with a low platinum loading, while at a higher Pt content the metallic Pt particles also appear. The prepared PtOx/TiO2 photocatalysts have been successfully tested in the production of hydrogen under UV light from aqueous solutions of ethanol and glucose, the products of starch biomass processing. Appreciable activity in the production of hydrogen from water/ethanol mixtures was achieved, even at a Pt content of up to 0.05%. PtOx/TiO2 photocatalysts with Pt content of 0.2–0.4 wt% have been successfully used to produce hydrogen from aqueous glucose solutions, and PtOx(0.29)/TiO2 photocatalyst has demonstrated an exceptionally high rate of H2 production per gram of platinum introduced and the quantum efficiency comparable to the highest published values.

Designing High Interfacial Conduction beyond Bulk via Engineering the Semiconductor-Ionic Heterostructure CeO2-δ/BaZr0.8Y0.2O3 for Superior Proton Conductive Fuel Cell and Water Electrolysis Applications.

Proton ceramic fuel cells (PCFCs) are an emerging clean energy technology; however, a key challenge persists in improving the electrolyte proton conductivity, e.g., around 10-3-10-2 S cm-1 at 600 °C for the well-known BaZr0.8Y0.2O3 (BZY), that is far below the required 0.1 S cm-1. Herein, we report an approach for tuning BZY from low bulk to high interfacial conduction by introducing a semiconductor CeO2-δ forming a semiconductor-ionic heterostructure CeO2-δ/BZY. The interfacial conduction was identified by a significantly higher conductivity obtained from the BZY grain boundary than that of the bulk and a further improvement from the CeO2-δ/BZY which achieved a remarkably high proton conductivity of 0.23 S cm-1. This enabled a high peak power of 845 mW cm-2 at 520 °C from a PCFC using the CeO2-δ/BZY as the electrolyte, in strong contrast to the BZY bulk conduction electrolyte with only 229 mW cm-2. Furthermore, the CeO2-δ/BZY fuel cell was operated under water electrolysis mode, exhibiting a very high current density output of 3.2 A cm-2 corresponding to a high H2 production rate, under 2.0 V at 520 °C. The band structure and a built-in-field-assisted proton transport mechanism have been proposed and explained. This work demonstrates an efficient way of tuning the electrolyte from low bulk to high interfacial proton conduction to attain sufficient conductivity required for PCFCs, electrolyzers, and other advanced electrochemical energy technologies.

Defect-rich MoS2/NiS2 nanosheets loaded on SiNWs for efficient and stable photoelectrochemical hydrogen production

Photoelectrochemical (PEC) reaction with efficient, stable, and cost-effective photocathodes using non-precious metals will be one of the most environmentally friendly technologies for hydrogen (H2) generation under the worldwide pressure for carbon neutrality. Herein, a new 3-dimentional (3D) SiNWs@MoS2/NiS2 photocathode was designed and synthesized. Defect-rich MoS2/NiS2 nanosheets on silicon nanowires (SiNWs) provide more active sites to promote charge transfer and photo-generated electron-hole separation. Meanwhile, the 3D structure of the photocathode provides an effective charge transfer mode and an open channel for rapid H2 release. The SiNWs@MoS2/NiS2 photocathode exhibits the maximum photocurrent density (21.4 mA·cm−2 at 0.9 V vs. RHE), highest H2 production rate (183 μmol·h−1), smallest diffusion resistance (34.7 Ω), and excellent catalytic stability for more than 10 h at pH = 7. Based on density function theory calculation, the MoS2/NiS2 nanosheets are conducive to chemical adsorption of H2 intermediates, which are crucial for the maintenance of the composite photocathode in PEC H2 production.

Photosynthesis assembling of ZCS/PO/Ni3Pi2 catalyst for three-stage photocatalytic water splitting into H2 and H2O2

Photocatalytic intermediate water splitting (PIWS) provides a promising route for hydrogen production as its high product value, favorable kinetics and easy separation. However, the traditional oxide and sulfide-based catalysts either respond to ultraviolet light or suffer from severe photocorrosion and sluggish kinetics, leading to poor conversion efficiency. Herein, we employ a two-step photosynthesis strategy to prepare an inexpensive phosphorus (PO) protection layer and nickel phosphate (Ni3Pi2) cocatalyst on the Zn0.14Cd0.86S (ZCS) photocatalyst, which shows a H2 and H2O2 evolution rate of 1.464 and 1.375 mmol h−1 g−1 in water splitting under 20 h visible light irradiation. The excellent PIWS performance originates from a combination of anti-photocorrosion ability of PO protection layer and bi-functional role of Ni3Pi2, which decompose into Ni2P and NiPi to enhance the H2 and H2O2 evolution. Moreover, the two-step photosynthesis process triggers photocatalytic partial water splitting (PPWS) by oxidizing NaH2PO2, with H2 evolution rate of 9.26 and 9.53 mmol h−1 g−1, respectively. This work develops a photosynthesis assembling of ZCS/PO/Ni3Pi2 catalyst, which not only presents superior performance for H2O2 evolution but also achieves a high average H2 production rate of 0.28 mmol h−1 under 25 h visible light irradiation by integrating the three-stage PPWS→PPWS→PIWS process.

Producing Hydrogen Energy Using Cr2O3-TiO2 Nanocomposite with Animal (Chitosan) Extract via Photocatalaysis

In this study, an efficient photocatalyst for water splitting was developed. The Cr2O3 and TiO2 nanoparticles (Cr2O3-TNPs) nanocomposite with (Chitosan extract) was created using ecologically friendly methods, such as the impregnation technique as TiO2 exhibits nano spherical (TNPs) shape structure. According to the researchers, this nanocomposite material enhanced its ability to absorb ultraviolet light while also speeding up the recombination of photogenerated electrons and holes. The TNPs and prepared Cr2O3-TNPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDX), and UV-visible absorbance. The XRD of TNPs showed a Tetragonal phase with 8.9 nm of average crystallite size and 14.2 nm for nanocomposite. FE-SEM images showed that the average particle size in the range of (12.5-57.5) nm and UV-VIS absorbance has energy gap of 3.8 eV, while the energy gap of Cr2O3-TNPs is 2.8 eV. It was found that the performance of photocatalysts of the nanocomposite for hydrogen generation was superior. It gave the highest rate of hydrogen production (3.6) ml at 80 min when exposed to ultraviolet light. Moreover, the nanocomposite revealed high H2 production rate under ultraviolt light irradiation (λ < 400 nm). The Cr2O3-TNps have high photocatalytic effectiveness due to their wide ultraviolt light photoresponse range and excellent separation of photogenerated electrons and holes.

Optimizing the Reaction Pathway by Active Site Regulation in the CdS/Fe2O3 Z-Scheme Heterojunction System for Highly Selective Photocatalytic Benzylamine Oxidation Integrated with H2 Production

Simultaneous photocatalytic H2 production and preparation of high-value chemicals by the selective oxidation of organic substances is of great significance for solar energy utilization and conversion. Herein, a Pt-modified 2D/2D CdS/Fe2O3 Z-scheme heterojunction was dexterously designed for photocatalytic dehydrogenation coupling of benzylamine with high performance and product selectivity. The Z-scheme charge transfer in CdS/Fe2O3 greatly boosts charge separation and maintains the strong redox capacity of photogenerated electrons and holes. Impressively, the loading of the Pt cocatalyst not only provides rich H2 production active sites to further accelerate charge separation and H2 production kinetics but also facilitates the condensation of N-benzylideneamine with benzylamine for N-benzylidenebenzylamine production and NH3 releasing. The selectivity for C═N coupling products is significantly enhanced and the C–C coupling side reaction is greatly suppressed. With sufficient benzylamine substrate and visible light irradiation, the optimal Pt/CdS/Fe2O3 composite displays a high H2 production rate of 39.4 mmol h–1 g–1 with a quantum efficiency of 32.81% at 420 nm, and the selectivity of benzylamine oxidation to N-benzylidenebenzylamine is above 90%.

Fabrication of Cu2O/MTiO3 (M = Ca, Sr and Ba) p-n heterojunction for highly enhanced photocatalytic hydrogen generation

Herein, a binary Cu2O/MTiO3 (M = Ca, Sr and Ba) p-n heterojunction composites are successfully designed and prepared by the hydrothermal method and following NaBH4 reduction treatment. With the help of ethanediol and polyvinylpyrrolidone, it is found that Cu2O nanoparticles (NPs) can disperse evenly on the surface of CaTiO3. Excitingly, the highest H2 production rate (HPR) of the Cu2O/CaTiO3 samples is up to 8.268 mmol g−1 h−1, which is about 344.5 times as high as that of CaTiO3 sample under the same conditions. Compared with pure CaTiO3, the photoelectric chemical performance tests manifest that photocurrent density the of Cu2O/CaTiO3 composite increases and the interface resistance decreases. These results manifest that the construction of p-n heterojunction in Cu2O/CaTiO3 sample can improve the separation and migration rates of photogenerated carrier pairs, thus accelerating the generation of H2. Additionally, the Cu2O/CaTiO3 exhibits the best HPR as compared to Cu2O/SrTiO3 and Cu2O/BaTiO3 composites, which may be attributed to the more active sites in hollow CaTiO3. This work reports a viable strategy to fabricate the Cu2O/MTiO3 p-n heterojunction, which can overcome the boundedness of single Cu2O or MTiO3 in photocatalytic performance.

Mechanism difference between nanoparticles and single-atom sites on aqueous formic acid dehydrogenation over coblat catalyst

Various Co-N-C catalysts including nanoparticles and single-atom sites were prepared using a low-temperature synthetic strategy by vacuum calcining with high exposure of the active sites and low energy consumption. When used in the formic acid (FA) dehydrogenation reaction, the obtained single-atom sites catalyst displayed high catalytic activity with a high H2 production rate of 27,361 mL·g−1·h−1. Moreover, the single-atom sites catalysts can still exhibit astonished catalytic performance in 88% FA (cheapest commercially available grade of FA) due to their super stability and special mechanism of reaction. From TEM, XRD, HAADF-STEM, XPS, and XANES characterization, the atomically dispersed active sites in the single-atom sites catalysts caused by strong metal-nitrogen coordination is believed to be the key to the success of this reaction. Moreover, the mechanism difference between nanoparticles and single-atom sites on aqueous formic acid dehydrogenation over coblat catalyst was illustrated.

Metal Mesh and Narrow Band Gap Mn0.5Cd0.5S Photocatalyst Cooperation for Efficient Hydrogen Production

A novel co-catalyst system under visible-light irradiation was constructed using high-purity metal and alloy mesh and a Mn0.5Cd0.5S photocatalyst with a narrow band gap (1.91 eV) prepared by hydrothermal synthesis. The hydrogen production rate of Mn0.5Cd0.5S changed from 2.21 to 6.63 mmol·(g·h)−1 with the amount of thioacetamide, which was used as the sulphur source. The introduction of Ag, Mo, Ni, Cu, and Cu–Ni alloy meshes efficiently improved the H2 production rate of the co-catalyst system, especially for the Ni mesh. The improvement can reach an approximately six times greater production, with the highest H2 production rate being 37.65 mmol·(g·h)−1. The results showed that some bulk non-noble metal meshes can act as good or better than some noble metal nanoparticles deposited on the main photocatalyst for H2 evolution due to the promotion of photoinduced electron transfer, increase in redox reaction sites, and prevention of the recombination of carriers.

Efficient H2 production in a novel separator electrode assembly (SEA) microbial electrolysis cell

MECs convert organics from wastewater to H2 as a fuel, which has a higher value than CH4 produced by anaerobic digestion. So far, the deterioration of H2 recovery during long-term operation is considered the most concerning obstacle for MEC development and is mainly caused by H2 consumption by exoelectrogens, methanogens, and homoacetogens, especially in a single-chamber MEC. Thus, reducing H2 consumption is of great scientific significance to improve effective H2 recovery in MECs. Previous studies have adopted diverse measures to reduce H2 consumption in MEC, but still not efficient and sustainable for long-term operation. Inspired by the design of a diaper, a novel configuration of separator-electrode assembly (SEA) was developed, where the cathode was sandwiched between a hydrophilic polyvinylidenedifluoride (PVDF) membrane and a hydrophobic polytetrafluoroethylene (PTFE) membrane. The porous PVDF membrane is highly water-permeable to separate anode and cathode, guarantee proton transfer, and form a “water barrier” to effectively block H2 crossover. The PTFE membrane is gas breathable to accelerate H2 diffuse out of the membrane to a gas collecting chamber and prevent water leakage. By the virtue of the SEA cathode design, SEA-MECs demonstrated a high current density of 482.5–515 A/m3 and a high H2 production rate of 4.53–5.02 m3/m3/d for over 30 days with up to 90 % cathodic hydrogen recovery rate, under 0.8 V of applied voltage without any chemical bacterial inhibitors. This study proves that a novel MEC configuration design is greatly important, and by no means, will shed light on effective H2 harvesting from wastewater.

Boosting hydrogen production from fermentation effluent of biomass wastes in cylindrical single-chamber microbial electrolysis cell.

Microbial electrolysis cells (MECs) are considered as green technologies for H2 production with simultaneously wastewater treatment. Low H2 recovery and production rate are two key bottlenecks of MECs fed with real H2 fermentation effluent of biomass wastes. This work established a 1 L cylindrical single chamber MEC and enriched electroactive anodic biofilms from cow dung compost to overcome the bottlenecks. These MEC components (platinum-coated cylindrical titanium mesh cathode and cylindrical graphite felt anode) were arranged in a concentric configuration. A high H2 production rate of 6.26 ± 0.23 L L-1day-1 with H2 yield of 5.75 ± 0.16 L H2 L-1 fermentation effluent was achieved at 0.8V. The degradation of acetate and butyrate (main components of H2 fermentation effluent) could reach to 95.3 ± 2.1% and 78.4 ± 3.6%, respectively. The microbial community analysis for anode showed the abundance of Geobacter (22.6%), Syntrophomonas (8.7%), and Dysgonomonas (6.3%) which are responsible to complex substrate oxidation, electrical current generation, and H2 production. These results prove the feasibility of cylindrical single-chamber MEC for high H2 production rate and high acetate and butyrate removal from H2 fermentation effluent.

Bandgap-engineered ferroelectric single-crystalline NBT-BT based nanocomposites with excellent visible light-ultrasound catalytic performance

Bandgap engineered ferroelectrics exhibit encouraging multi-energy catalytic performance by coupling the piezoelectricity and photoexcitation, which shows immense potential for environmental remediation and fuel production. However, it is challenging to prepare nano single-crystalline ferroelectric piezo-photoelectric with strong visible light absorption ability. Here, Ni mediated NBT-BT(NBT-BNT) single-crystalline nanocubes around 100 nm with considerable visible light absorption were synthesized by a high-temperature hydrothermal method. The mechanism of Ni2+ on the formation of NBT-BT nanocubes was proposed. The catalytic efficiency of NBT-BNT nanocubes is enhanced by decorating carbon quantum dots (CQDs). The RhB can be degraded within 8 min and the hydrogen production rate reaches up to ∼350 μmol g-1h-1 under visible light-ultrasonic condition. Moreover, under the simulated sunlight-ultrasound condition, RhB can be degraded within merely 3 min and a high H2 production rate of ∼747 μmol g-1h-1 is achieved. This work presents a paradigm for preparing ferroelectric single-crystalline nanocatalysts for multi-energy catalytic application.

Template-free hierarchical trimetallic oxide photocatalyst derived from organically modified ZnCuCo layered double hydroxide

High-performance photocatalysts have considerable potential to address energy and environmental issues. In this study, dodecylbenzenesulfonate (DBS) modified ZnCuCo layered double hydroxide (DBS-ZnCuCo LDH) microspheres were synthesized through the facile template-free hydrothermal method. Subsequently, ZnCuCo mixed-metal oxides (MMOs) with morphological features of the DBS modified LDH, enhanced surface area, increased light absorption and effective charge separation were prepared by the calcination of the as-synthesized LDH at 650 °C. Structural, morphological, and photoelectrochemical properties of ZnCuCo and DBS-ZnCuCo LDHs and the corresponding MMOs (ZnCuCo MMO1 and ZnCuCo MMO2) were investigated. SEM and TEM images revealed that DBS-ZnCuCo LDH and ZnCuCo MMO2 possess 3D flower-like hierarchical morphologies with interlaced petal-like nanosheets. Although ZnCuCo LDH was inactive for photocatalytic H2 production under visible light irradiation, ZnCuCo MMO2 exhibited a high H2 production rate (3700 μmol g−1 h−1), benefiting from the synergy of the ZnO, CuO, and Co3O4. Furthermore, 95% sulfamethazine (SMZ) degradation was obtained after 60 min of photocatalysis, which is considerably higher than the degradation efficiency of ZnCuCo LDH (24%) and ZnCuCo MMO1 (58%). Based on the photoelectrochemical tests, Z-scheme and double charge transfer mechanisms were proposed to explain the enhanced photocatalytic H2 production and degradation of SMZ. Scavenging tests revealed that O2•− radicals were the main reactive species in the photodegradation of SMZ. A possible degradation pathway was proposed based on the detection of intermediate products.

Ultrathin Two-Dimensional ZnIn2S4/Nix-B Heterostructure for High-Performance Photocatalytic Fine Chemical Synthesis and H2 Generation.

Photocatalytic H2 evolution coupled with organic transformation provides a new avenue to cooperatively produce clean fuels and fine chemicals, enabling a more efficient conversion of solar energy. Here, a novel two-dimensional (2D) heterostructure of ultrathin ZnIn2S4 nanosheets decorated with amorphous nickel boride (Nix-B) is prepared for simultaneous photocatalytic anaerobic H2 generation and aromatic aldehydes production. This ZnIn2S4/Nix-B catalyst elaborately combines the ultrathin structure advantage of the ZnIn2S4 semiconductor and the cocatalytic function of Nix-B. A high H2 production rate of 8.9 mmol h-1 g-1 is delivered over the optimal ZnIn2S4/Nix-B with a stoichiometric production of benzaldehyde, which is about 22 times higher than ZnIn2S4. Especially, the H2 evolution rate is much higher than the value (2.8 mmol h-1 g-1) of the traditional photocatalytic half reaction of H2 production with triethanolamine as a sacrificial agent. The apparent quantum yield reaches 24% at 420 nm, representing an advanced photocatalyst system. Moreover, compared with traditional sulfide, hydroxide, and even noble metal modified ZnIn2S4/M counterparts (M = NiS, Ni(OH)2, Pt), the ZnIn2S4/Nix-B also maintains markedly higher photocatalytic activity, showing a highly efficient and economical advantage of the Nix-B cocatalyst. This work sheds light on the exploration of 2D ultrathin semiconductors decorated with novel transition metal boride cocatalyst for efficient photocatalytic organic transformation integrated with solar fuel production.

Synthesis of g-C3N4/NiO-carbon microsphere composites for Co-reduction of CO2 by photocatalytic hydrogen production from water decomposition

In this paper, a g-C3N4/NiO/corn straw derivative carbon microsphere composite photocatalyst was successfully prepared. Photoelectric studies show that a heterojunction was formed between g-C3N4 and NiO nanosheets, and the graphitized carbon microspheres were successfully modified on g-C3N4 and NiO nanosheets. The heterostructure between g-C3N4 and NiO works synergistically with the conductivity of carbon microsphere, resulting in H2 production and CO2 reduction in photocatalysis. Photocatalytic experiments show that the photocatalytic performance of g-C3N4/NiO/carbon microsphere composite is enhanced, and the highest H2 production rate was 36–58 times higher than that of pure g-C3N4. In the presence of CO2 gas, H2 production and CO2 reduction occur simultaneously. The possible mechanism of H2 production combined with CO2 reduction photocatalysis is analyzed from the perspective of thermodynamics and kinetics. The g-C3N4/NiO/carbon microsphere composite has a stronger H2 evolution performance than CO2 reduction performance. The change in free energy (ΔG) for the conversion of CO* to free CO gas is 0.52 eV, and CO release is the key step affecting the synergistic reduction of CO2 by H2. This study provides new strategies for the synergistic reduction of CO2 by photocatalytic technology for H2 production.

Effect of Hydrogen Peroxide on Hydrogen Production from Melon Fruit (Cucumis melo L.) Waste by Anaerobic Digestion Microbial Community

Biohydrogen (H2) production has the potential to provide clean, environmentally friendly, and cost-effective energy sources. The effect of increasing oxidative stress on biohydrogen production by acid-treated anaerobic digestion microbial communities was studied. The use of varying amounts of hydrogen peroxide (H2O2; 0.1, 0.2, and 0.4 mM) for enhancing hydrogen production from melon fruit waste was investigated. It was found that H2O2 amendment to the H2-producing mixed culture increased hydrogen production. Treatment with 0.4 mM H2O2 increased cumulative H2 output by 7.7% (954.6 mL/L), whereas treatment with 0.1 mM H2O2 enhanced H2 yield by 23.8% (228.2 mL/gVS) compared to the untreated control. All treatments showed a high H2 production rate when the pH was 4.5 – 7.0. H2O2-treated samples exhibited greater resilience to pH reduction and maintained their H2 production rate as the system became more acidic during H2 fermentation. The application of H2O2 affected the volatile fatty acid (VFA) profile during biohydrogen fermentation, with an increase in acetic and propionic acid and a reduction in formic acid concentration. The H2O2 treatment positively affects H2 production and is proposed as an alternative way of improving H2 fermentation.