Hydrogen Production Research Articles

New insights into microalgal photobiological hydrogen production: Potential role of aggregation forms in modulating the hydrogenase activity and metabolic properties of microalgae during hydrogen production

Photobiological hydrogen production of microalgae is highly influenced by environmental conditions, and the appropriate microalgal aggregation form is conducive to microalgae overcome environmental limitations and increase their hydrogen production capacity. In this study, the effects of three aggregation methods including self-flocculation, biofilm attachment, and gel immobilization on the photobiological hydrogen production of both prokaryotic Synechocystis sp. and eukaryotic Chlamydomonas reinhardtii were investigated. The results indicated that microalgal aggregates formed via gel immobilization exhibited superior physicochemical properties such as porosity, integrity, and oxygen diffusion coefficients, creating favorable conditions for enhanced hydrogenase activity. Upon gel-immobilization, hydrogen production of Synechocystis sp. and C. reinhardtii exhibited an increase of 1.89 and 2.02-folds, respectively, compared with suspended microalgae. Concurrently, hydrogenase activities increased to 2.07 and 32.9 H2/(mg chlorophyll·h), respectively. The gel-immobilized aggregate form prompted the microalgae to maintain a relatively high photosynthetic activity, with the electron transfer rate reaching more than 1.58 folds of the control. Notably, three aggregated forms also accelerated oxygen consumption, and intracellular organic matter degradation, thereby optimizing electron utilization by microalgal hydrogenase. Furthermore, aggregation up-regulated hydrogenase gene expression in both species, particularly in gel-immobilized groups (2.34- and 4.14-folds increase compared with the control for Synechocystis sp. and C. reinhardtii, respectively). Subsequently, significantly upregulated gene expression related to oxidative phosphorylation and antioxidant systems was observed in C. reinhardtii aggregates, correlating with its relatively higher increase in hydrogen production compared with Synechocystis sp. aggregates. This study elucidated the mechanism by which aggregation strengthens microalgal hydrogen production and offers insights crucial for its industrialization.

A kinetic study of nonthermal plasma pyrolysis of methane: Insights into hydrogen and carbon material production

Nonthermal plasma-assisted methane pyrolysis has emerged as a promising approach for hydrogen production under mild conditions while simultaneously yielding valuable carbon materials. Herein, we develop a plasma chemical kinetic model to elucidate the underlying reaction mechanisms involved in methane pyrolysis to hydrogen and solid carbon within a gliding arc (GA) reactor. A zero-dimensional (0D) chemical kinetics model was developed to simulate the plasma chemistry during the GA-based methane pyrolysis process, incorporating reactions involving electrons, excited species, ions, and heavy species. The model accurately predicted methane conversion and product selectivity in agreement with the experimental data. A strong correlation between hydrogen production and methane conversion was observed, primarily driven by the reaction CH4 + H → CH3 + H2, contributing 44.2% to hydrogen formation and 37.7% to methane depletion. Electron impact collisions with hydrocarbons play a secondary role, accounting for 31.1% of H2 formation. This work provides a detailed investigation into the mechanism of solid carbon formation in GA-assisted methane pyrolysis. Most of the solid carbon originates from the electron impact dissociation of C2H2 through reactions e + C2H2 → e + C2 + H2/2H and subsequent C2 condensation. C2 radicals are highlighted as the major contributors to solid carbon formation, accounting for 95.0% of the total carbon yield, which might be due to the relatively low C–H dissociation energy in C2H2. This kinetic study offers a comprehensive understanding of the mechanisms behind H2 and solid carbon formation during GA-assisted methane pyrolysis.

Porous and defective NiCo2O4 spinel derived from bimetallic NiCo-based Prussian blue analogue for enhanced hydrogen production via the urea electro-oxidation reaction

The efficient hydrogen production via overall water splitting is seriously restrained by the slow kinetics of the oxygen evolution reaction (OER). The substantially low potential for the urea electro-oxidation reaction (UOR) can tackle this problem by replacing the OER at the electrolyzer anode. Herein, the NiCo2O4 spinel with rich oxygen vacancies (Ov) and embedded within mesoporous carbon network (Ov-NiCo2O4@mC) was derived from NiCo-based Prussian blue analogous (NiCo PBA) and exploited as the bifunctional electrocatalyst of the UOR and OER for boost the hydrogen production via the overall water splitting. Benefiting to the regular skeleton and abundant dual metal sites of NiCo PBA, the derived Ov-NiCo2O4@mC comprises abundant oxygen vacancies, lattice defects, and adjustable electron structure. These features afford Ov-NiCo2O4@mC the improved UOR ability, showing the potential of 1.33 V versus reversible hydrogen electrode (RHE) at the current density of 10 mA cm−2, along with a small Tafel slopes of 31 mV dec-1, remarkably lower than that of the OER (1.51 V versus RHE, Tafel slope = 85 mV dec-1). The UOR performance of Ov-NiCo2O4@mC substantially outperforms to most of the reported Co and/or Ni-based electrocatalysts. Impressively, the assembled two-electrode urea-assisted overall water splitting device shows the small voltage for the hydrogen production (1.43 V versus RHE) and good long-term stability. The present work can provide a new alternative for the efficient hydrogen production using the MOFs-derivatives.

Graphitic carbon nitride nanosheets decorated with HAp@Bi2S3 core–shell nanorods: Dual S-scheme 1D/2D heterojunction for environmental and hydrogen production solutions

By combining different semiconductors, scientists have developed innovative materials capable of converting solar energy into useful forms of energy or driving chemical reactions that clean up pollutants. These materials offer a promising path to combat global environmental and energy challenges. In this study, HAp@Bi2S3 core–shell structures were synthesized using a facile microemulsion technique, and then loaded onto graphitic carbon nitride via a hydrothermal method to create an advanced HAp@Bi2S3/g-C3N4 dual S-scheme heterojunction. The engineered heterojunction exhibited enhanced hydrogen production and visible light photocatalytic oxidation of metronidazole. The improved photocatalytic efficiency was attributed to the core–shell structure of HAp@Bi2S3 along with the formation of a dual S-scheme heterojunction in HAp@Bi2S3/g-C3N4. As a result, the novel dual S-scheme HAp@Bi2S3/g-C3N4 heterojunction demonstrated a significantly higher hydrogen production rate, ca. 20 times higher than that of hydroxyapatite (HAp), 11 times higher than Bi2S3, and 5 times higher than the HAp@Bi2S3. This research introduces a novel approach to crafting dual S-scheme heterojunctions based on Bi2S3, which enables swift electron transfer across heterojunction interfaces, thereby enlarged possibility windows to sustainable hydrogen production and wastewater remediation technologies.

Performance of a pilot-scale microbial electrolysis cell coupled with biofilm-based reactor for household wastewater treatment: simultaneous pollutant removal and hydrogen production.

The septic tank is the most commonly used decentralized wastewater treatment systems for household wastewater treatment in on-site applications. The removal rate of various pollutants is lower in different septic tank configurations. The integration of a microbial electrolysis cells (MEC) into septic tank or biofilm-based reactors can be a green and sustainable technology for household wastewater treatment and energy production. In this study, a 50-L septic tank was converted into a 50-L MEC coupled with biofilm-based reactor for simultaneous household wastewater treatment and hydrogen production. The biofilm-based reactor was integrated by an anaerobic packed-bed biofilm reactor (APBBR) and an aerobic moving bed biofilm reactor (aeMBBR). The MEC/APBBR/aeMBBR was evaluated at different organic loading rates (OLRs) by applying voltage of 0.7 and 1.0V. Result showed that the increase of OLRs from 0.2 to 0.44kg COD/m3 d did not affect organic matter removals. Nutrient and solids removal decreased with increasing OLR up to 0.44kg COD/m3 d. Global removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), ammoniacal nitrogen (NH4+), total phosphorus (TP) and total suspended solids (TSS) removal ranged from 81 to 84%, 84 to 85%, 53 to 68%, 88 to 98%, 11 to 30% and 76 to 88% respectively, was obtained in this study. The current density generated in the MEC from 0 to 0.41 A/m2 contributed to an increase in hydrogen production and pollutants removal. The maximum volumetric hydrogen production rate obtained in the MEC was 0.007 L/L.d (0.072 L/d). The integration of the MEC into biofilm-based reactors applying a voltage of 1.0V generated different bioelectrochemical nitrogen and phosphorus transformations within the MEC, allowing a simultaneous denitrification-nitrification process with phosphorus removal.

Can hydrogen be generated by UV- photodegradation of biomass residues in water media?

The photoinduced processes can be promising routes for hydrogen generation. This study explores hydrogen production through the non-catalyzed photodegradation of various biomass materials, a process that remains largely understudied compared to the catalyzed ones, i.e., photoreforming. Using as precursor almond shell (AS), a lignocellulosic biomass residue, various solid and liquid materials obtained from it were tested as substrates. These materials were obtained through different pretreatment methods including grinding, milling, pyrolysis, and hydrothermal carbonization (HTC), and compared with milled cellulose (MC). Photodegradation tests, conducted in aqueous media under UV light, revealed that hydrogen production strongly depends on the structural and compositional features of the substrates. Among the solid samples, ground almond shell (GAS) and milled cellulose (MC) showed promising hydrogen yields. However, the liquid residue from the HTC process using diluted phosphoric acid (HMAS-L2), which is rich in simple organic acids, stood out, delivering the highest hydrogen production across all the substrates, and reaching an impressive value of 105 μmol of H2 in 5 h of reaction. Attention was also given to the production of other gases, particularly carbon dioxide and methane, as a result of the photodegradation. CO2 production occurred for all the substrates. PMAS (the pyrolyzed milled almond shell) and, specifically, HMAS-L2 generated detectable amounts of CH4 (5 and 22 μmol, respectively).The H2/CO2 ratios reached 0.66 for MC and 0.44 for HMAS-L2, highlighting the interest in evaluating the non-catalyzed biomass photodegradation as a preliminary step for future photoreforming studies. These findings enhance our understanding of biomass-based hydrogen generation and open new avenues for exploring non-catalyzed photoinduced processes.

A new carbon-negative hydrogen production cycle for better sustainability

Carbon dioxide removal is considered by many as an essential piece to achieve global net zero targets which was also mentioned by the third working group of Intergovernmental Panel on Climate Change. On top of this, green hydrogen is badly needed to achive carbon-free society long-term sustainability. This study proposes a new five-step sodium hydroxide thermochemical cycle for simultaneous hydrogen production and carbon dioxide removal, which is driven by the heat at least 400 °C. The proposed integrated cycle can be driven by clean energy sources that can be utilized to generate heat at required temperatures. The proposed system is designed and analyzed by using energy and exergy approaches of thermodynamics. A case study is also developed in order to understand the effects of changing parameters on system performance. A thermochemical hydrogen production cycle is designed with an unequilibrium reaction where the respective heat capacity calculation models are employed. According to the calculations, more than half of the energy content of process heat can be converted into hydrogen, where maximum energy and exergy efficiencies of the thermochemical cycle are found as 50.05% and 76.61% when the separation reaction is carried out at 400 °C. According to the case study results, a parabolic trough collector type concentrated solar energy system with 295 kW of heat sink capacity, can generate 5216.65 kg of hydrogen and capture 19,991.97 kg of carbon dioxide in a location where 1500.11 kWh of solar energy is reached per m2 of area in a typical year.

Stability analysis and multi-objective optimization of methanol steam reforming for on-line hydrogen production

The potential solution to hydrogen storage and transportation challenges is provided by liquid fuel-based on-line hydrogen production. An online hydrogen production device has been constructed and the stable output of hydrogen at 6.8 bar under dynamic conditions of 6–13 Nm3/h has been achieved. To achieve optimal economic and thermodynamic performances, the mathematical models for mass, energy, and techno-economics are constructed based on field test data. The Non-Dominated Sorting Genetic Algorithm is employed to update temperature splitting points between multi-stage heat exchangers, targeting multi-objective optimization of heat exchange area, system energy efficiency, and annual average cost. Pareto optimal solutions indicate that such optimization can improve system energy efficiency by 0.03%–3.76% and decrease the hydrogen production cost from 0.004 $/kg to 0.599 $/kg. This work demonstrates the feasibility and effectiveness of multi-objective optimization for online hydrogen production system design and offers important guidance for decision-making in heat exchange network schemes.

Au/Ag@ZnS yolk-shell photocatalysts enhanced with noble metals and hyaluronic acid for efficient hydrogen production in rheumatoid arthritis therapy

Rheumatoid arthritis, characterized by the abnormal proliferation of synovial cells and extensive macrophage infiltration, is a chronic inflammatory disease. Molecular hydrogen, known for its antioxidant properties, has shown promise in eliminating reactive oxygen species. However, the low solubility and bioavailability of hydrogen limit the effectiveness of this therapy. To overcome these issues, we developed a novel yolk-shell heterostructure, H-AAZS (Au/Ag@ZnS modified hyaluronic acid), utilizing a hydrothermal cation exchange process. Through ion doping, semiconductor hybridization, and Schottky barriers in H-AAZS, photocatalysis for hydrogen generation has been successfully implemented using 660 nm laser irradiation. Additionally, the H-AAZS demonstrate the capacity for mild photothermal therapy, inducing apoptosis in synovial cells with Au's hot electrons with 660 nm laser irradiation. This strategy not only improves the abnormal proliferation of synovial cells but also avoids the exacerbation of inflammation caused by thermal stimulation. Both in vitro and in vivo experiments validate the synergistic effects of hydrogen production mediated anti-inflammatory responses, macrophage polarization and photothermal therapy. Therefore, this work represents a significant advancement as it ingeniously harnesses photocatalysis to modulate the synovial microenvironment while mitigating the side effects associated with photothermal therapy. This nanocrystal provides new and valuable insights into the potential treatment of Rheumatoid arthritis.

Assessment of a coupled electricity and hydrogen sector in the Texas energy system in 2050

Due to its ability to reduce emissions in the hard-to-abate sectors, hydrogen is expected to play a significant role in future energy systems. This study modifies a sector-coupled dynamic modeling framework for electricity and hydrogen by including policy constraints, carbon prices, and possible hydrogen pathways and applies it to Texas in 2050. The impact of financial policies, including the US clean hydrogen production tax credit, on required infrastructure and costs are explored. Due to low natural gas prices, financial levers are necessary to promote low-carbon hydrogen production as the optimized solution. The Levelized Costs of Hydrogen are found to be $1.50/kg in the base case (primarily via steam methane reformation production) and lie between $2.10 - 3.10/kg when production is via renewable electrolysis. The supporting infrastructure required to supply those volumes of renewable hydrogen is immense. The hydrogen tax credit was found to be enough to drive production via electrolysis.

Cathodic corrosion induced selective nano-crystallization of Nickel oxo/hydroxo complex on (NiFeCr)SiB amorphous ribbon for alkaline oxygen evolution reaction and methanol oxidation reaction

The study focuses on the development and optimization of (Ni87Fe4Cr9)78Si8B14 amorphous ribbons as self-supported electro-catalysts for oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Electro-catalytically active nano α-Ni(OH)2 phase (5–10nm) was generated in the amorphous ribbon surface through potentiostatic cathodic corrosion for different time intervals (0–120 min). The X-ray diffraction and scanning electron microscopy results shows the favourable occurrence of dense nanocrystallization of α-Ni(OH)2 between 45 and 90 min of corrosion time. For OER in 1 M KOH, the 60-min surface modified ribbon exhibits an overpotential of 295 mV at 10 mA/cm2 current density and tafel slope of 51 mV dec−1. In case of MOR in 1 M KOH +1 M MeOH, the 90-min corroded ribbon shows lowest potential of 1.38 V vs RHE, at 10 mA/cm2 and tafel slope of 34 mV dec−1. In addition to superior electro-catalytic activity, the optimal surface-modified ribbons show superior long-term stability for OER and MOR studies, indicating its potential application in hydrogen generation and direct methanol fuel cell.

Unlocking glycerol Potential: Novel pathway for hydrogen production and Value-Added chemicals

In the global fight against climate change, the bio-based supply chain represents an interesting solution as it offers the potential to produce high-value-added products and bioenergy through the utilization of waste and by-products. In this work, a new route is proposed for the conversion of bio-based glycerol to H2/CO2 and high value-added liquid and solid products. The innovative process used pure or crude glycerol or ethanol-glycerol mixture along with water and sodium metaborate as reagents at 300 °C under discontinuous conditions. The gas stream consists mainly of hydrogen, followed by biogenic CO2 (31–54 %), CO (4–13 %) and CH4 in traces. The presence of water in the tested crude glycerol improved the hydrogen selectivity to 55 %. Characterization of the liquid reaction products revealed the synthesis of products such as 1,2-propanediol, propanoic acid, acetic acid, cyclopentenones and cyclic diglycerol. In the solid phase, an aliphatic hydrocarbon resin with oxygenated carbon along the saturated chain and an aromatic cluster were also characterized by NMR, FTIR and TG analyses. Based on these findings, the global reaction route to the general reaction products was proposed.

Enhanced Oxygen Evolution Reaction in Alkaline Water Electrolysis Using Bimetallic NiFe Metal-Organic Frameworks Integrated with Carbon Nanotubes

Hydrogen is considered a very clean and highly available renewable energy resource for the future. Water electrolysis (WE) is a conspicuous promising technology to produce hydrogen on a large scale, without generating carbon dioxide. In this study, we prepared bimetallic NiFe-based metal–organic frameworks (MOFs) integrated with CNTs (NiFe–BTC@CNTs) as highly efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline water electrolysis. Combining NiFe MOFs and CNTs significantly enhanced the electrochemical performance and structural integrity of the catalyst. The NiFe–BTC@CNT (30 wt.% CNTs) demonstrates a significant low overpotential of 230 mV at 10 mA·cm⁻2, superior catalytic activity with a Tafel slope of 36 mV·dec⁻1, and excellent stability under both constant and dynamic operating conditions. These unique characteristics are attributed to the high surface area and abundant active sites provided by the bimetallic MOF structure, combined with the exceptional electrical conductivity and mechanical strength of CNTs. Furthermore, the integration of CNTs improves the dispersion while preventing the agglomeration of MOF particles, ensuring a more uniform and accessible active surface area. This research highlights the potential of the NiFe–BTC@CNT catalysts as high-performance durable electrocatalysts for sustainable hydrogen production, offering a significant advance in the development of advanced materials for energy conversion and storage applications.

Enhanced charge transfer kinetics across the graphdiyne-metal sulfide ohmic interface for boosting photocatalytic hydrogen evolution

The design and construction of photocatalysts are the crucial step for solar-driven hydrogen evolution. Herein, a new type of graphdiyne (CnH2n-2)-based photocatalyst, which was prepared by one pot method, was used to promote hydrogen evolution reaction by constructing GDY/VS2 ohmic junction with S sites anchoring on the surface. Actually, the unique two-dimensional conjugated carbon network of GDY can maintain the structural stability. The uneven surface facilitates the flow of electrons, which makes GDY a good electron donor. In addition, the expanded interlayer spacing of VS2 exposes more hydrogen evolution active sites. The increase in surface electronegativity of composite catalysts enhances their redox ability and charge transfer kinetics. The band edge of the graphdiyne-metal sulfide Ohmic contact interface is bent, allowing electrons to flow into the co catalyst without resistance. These synergistic effects lead to the robust hydrogen production of GDY/VS2, which was increased by nearly 10.3 times compared with that of pure GDY. Finally, charge migration at the interface of graphdiyne-metal sulfide heterojunction was proposed and further verified combining in situ XPS and theory calculation. This research marks a significant stride for enhance the efficiency of photocatalytic hydrogen evolution by designing and constructing composite heterojunction materials.

Natural DNA-Derived Ultrafine Ir/Ir2P Hybrid on Porous N, P-Codoped Carbon for pH-Universal Energy-Saving Hydrogen Production Assisted by Electrocatalytic Hydrazine Oxidation

Due to the intrinsic slow kinetics and high potential of the anodic oxygen evolution reaction (OER), hydrazine oxidation reaction (HzOR) with ultralow potential is a viable substitute to combine the cathodic hydrogen evolution reaction (HER) for the energy-saving hydrogen generation. Therefore, it is a compelling demand to explore high-performance electrocatalysts for bifunctional HER and HzOR. Herein, natural DNA was employed to prepare the uniform and ultrafine Ir/Ir2P hybrids loaded on N, P-codoped porous carbon (Ir/PNPC) through a facile “mix-and-pyrolyze” approach. Benefitting from abundant heteroatom doping, large surface area and high degree of graphitization, Ir/PNPC only requires the ultrasmall potentials of -22/-347/-54 mV at 100 mA cm-2 for HER, 46/172/227 mV at 10 mA cm-2 for HzOR, and 167/836/864 mV at 100 mA cm−2 for the constructed two-electrode overall hydrazine splitting (OHzS) in the alkaline, neutral and acidic electrolytes, respectively, all exceeding Pt/C and also showing the remarkable energy-efficient superiority over the conventional water splitting. Furthermore, the OHzS system can be readily driven by the as-prepared direct N2H4/H2O2 fuel cell and commercial solar cell with decent H2 generation rate of 1.245 and 1.392 mmol h-1, respectively. This study provides lights on the preparation of the advanced pH-universal HER and HzOR bifunctional electrocatalysts by natural DNA and is also encouraging for the energy-saving H2 production.

In-situ fabrication of defect rich Cu2+1O on electrodeposited Cu cone arrays for promoting electrocatalytic anode hydrogen production

The low-potential formaldehyde oxidation reaction (FOR) is a significant replacement for oxygen evolution reaction, as FOR can couple with the cathode hydrogen evolution reaction (HER) to obtain a bipolar H2 production system with an extra low cell voltage. Cu-based electrocatalysts offer cost advantages in FOR but suffer from poor intrinsic activity and stability. Herein, a novel defect rich CF-Cu@Cu2+1O/Cu pinecone-shaped array electrocatalyst is fabricated by in-situ solution immersion of electrodeposited Cu cone arrays on foam for efficient and stable formaldehyde selective oxidation reaction to co-produce hydrogen and valuable formate. Benefitting from the partially mixed Cu2+1O in metallic copper and concomitant production of defect rich oxygen vacancies, only 0.04 VRHE is required for electrocatalytic FOR at 100 mA·cm−2 under alkaline conditions. FOR current density of CF-Cu@Cu2+1O/Cu electrode exhibits 2.35 times than that of CF-Cu (144 mA·cm−2) and 77 times than that of copper foam (4.4 mA·cm−2) at 0.5 VRHE. Moreover, the special pinecone-shaped structure is constructed to modify Cu-based catalysts with substantially enhanced stability. A FOR-HER co-electrolysis device of CF-Cu@Cu2+1O/Cu(+)||Pt/C(−) can achieve bipolar H2 production with an approaching 200 % Faradaic efficiency, requiring an extremely low electrical energy consumption of only ∼ 0.35 kWh per m3 of H2 and potential of 0.291 V at 100 mA·cm−2 at room temperature.

Optimizing waste heat recovery for hydrogen production: Modeling and simulation of ternary size metallic granule flow in a cooling cylinder

In order to recover the waste heat of high temperature metallic granules to produce steam for hydrogen production, a waste heat recovery cooling cylinder with cooling water channel is innovatively developed. The simulation is carried out based on DEM and soft sphere model to study the flow characteristics of ternary size metallic granules. The model of cooling cylinder is established and verified by comparing to the experiment data. The change rule of bed shape in the waste heat recovery cooling cylinder is examined, and the inclination angle, rotational speed and filling rate are assessed to find their influence on the flow characteristics of ternary size metallic granules. The results indicated that, with the increase of inclination angle, the axial velocity increases by 482.76%, which means the reduce of residence time of granules. With the increase of rotational speed, the axial velocity has an increase of 161.54%, the sum velocity increases by 158.49%, leading to a decrease of residence time. As the filling rate increases from 1.5% to 15.5%, the contact number has an increase of 91.53%, which lead to the increase of heat transfer area. The residence time and heat transfer area will directly affect the waste heat recovery efficiency, so a proper arrangement of granule flow is significant for enhancing the heat transfer efficiency.

Utilizing cationic vacancies to enhance nickel-cobalt layered double hydroxides for efficient electrocatalytic urea oxidation reaction

Electrocatalytic urea oxidation reaction (UOR) is a promising approach for urea-rich wastewater splitting, which benefits for reducing energy consumption in hydrogen production accompanying environmental protection and sustainable energy development. To address the limitations posed by the self-oxidation of nickel-based catalysts on the activity of UOR, we here developed a NiCo LDH nanosheet catalyst with abundant Ni vacancies to initiate the UOR process prior to nickel oxidation. Electrochemical impedance spectroscopy and In-situ spectroscopic characterizations confirm that the UOR process primarily occurs on the surface of the catalyst, rather than being driven by nickel oxidation products. The favorable electronic structure modulation induced by Ni vacancies makes the catalyst more energetically favorable for the UOR compared to nickel self-oxidation. The catalyst exhibits excellent UOR activity, only requiring 1.27 V vs. RHE at 10 mA cm−2 and 1.34 V vs. RHE at 100 mA cm−2, with no significant decay observed after over 120 h of operation. Furthermore, it can function as a bifunctional catalyst, requiring only 1.66 V to achieve 100 mA cm−2 for the UOR||HER system. This study expands the pathway for the application of cationic vacancies in UOR.

A novel PEMFC-GT-ST power generation system employing supercritical water gasification of coal for enhanced hydrogen production

This study presents an innovative coal-fired power generation system that integrates a Proton Exchange Membrane Fuel Cell (PEMFC), Gas Turbine (GT), and Steam Turbine (ST) with a supercritical water gasification (SCWG) process designed to efficiently convert coal into hydrogen. A pivotal feature of this system is the first-time integration of advanced two-step SCWG technology with PEMFC, which significantly boosts hydrogen yield, thereby elevating overall efficiency. By effectively addressing the thermodynamic limitations of the Carnot cycle, the proposed system achieves an impressive coal-to-electricity conversion efficiency of 51.61%. Economic viability is demonstrated through a competitive levelized cost of energy (LCOE) of $0.052 per kWh and a rapid payback period of approximately 2.87 years. Furthermore, the study analyzes the impact of various operational parameters—such as coal feed capacity, water-to-coal ratio, operating temperatures of the PEMFC, fuel utilization rates, airflow, and hydrogen bypass flow—on system performance. The findings not only advance the efficiency of coal-to-electricity conversion but also contribute valuable insights to the evolution of sustainable coal-fueled power generation technologies.

Enhanced photocatalytic hydrogen evolution via yolk–heteroshell TiO2@TiO2/SiO2 nanoreactor with confined Pt nanoparticles

The upper limit of photocatalytic efficiency is largely determined by the light-harvesting capability of a semiconductor. To address this challenge, we developed a yolk-heteroshell TiO2@TiO2/SiO2 (T@T/S) nanoreactor, leveraging a novel design based on an in-depth understanding and innovative utilization of light-matter interactions. The T@T/S nanoreactor significantly enhances solar light capture and utilization efficiency through total internal reflection mechanisms facilitated by the heterogeneous shell. This heteroshell, consisting of an outer SiO2 shell an inner monolayer of TiO2 nanoparticles, maximizes light confinement due to the different refractive indices of SiO2 and TiO2, while also minimizing mass transfer resistance due to the thin inner shell layer. These unique structural features result in high photocatalytic activity under simulated solar light. Additionally, we successfully applied a “ship-in-a-bottle” strategy for the confined growth of platinum nanoparticles within T@T/S nanoreactor. The Pt0.5-T@T/S nanoreactors demonstrated excellent hydrogen production, achieving a hydrogen evolution rate of 24.43 mmol g−1h−1 under simulated sunlight and an apparent quantum efficiency (AQE) of 7.8 % at 350 nm. This study highlights the importance of nano-engineered designs in optimizing semiconductor photocatalysts and shows the significant potential of our approach for sustainable energy conversion and environmental protection.