Stable Hydrogen Production Research Articles

Revealing the In Situ Evolution of Tetrahedral NiMoO4 Micropillar Array for Energy‐Efficient Alkaline Hydrogen Production Assisted by Urea Electrolysis

The great promise of the combination of urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) to simultaneously achieve wastewater treatment and hydrogen production calls for the rational design of high‐performance electrocatalysts. Herein, the reconstruction with the formation of Ni2P and Mo2O72− on the surface can largely enhance the alkaline HER activity of P‐NiMoO4 by on‐site electrochemical activation strategy. Systematic experimental results indicate that the reconstruction process enables the exposure of additional Ni sites and the adjustment of hydrogen adsorption to facilitate HER kinetics. Ultimately, a highly efficient alkaline HER electrode with low overpotential of −48.9 mV for 10 mA cm−2 is achieved. More importantly, a UOR electrolyzer assembled with A‐P‐NiMoO4 as the cathode and P‐NiMoO4 as the anode exhibits impressive performance with a small cell voltage of 1.363 V for 10 mA cm−2. The application of the fabricated electrodes in a practical cell driven by a commercial dry battery (1.5 V) demonstrates efficient and stable hydrogen production, making the developed strategy promising for the rational design of highly active electrocatalysts for green hydrogen production.

Integration of the PEMFC with a hydrogen production device adopting sodium borohydride and metal cobalt catalyst

Hydrolysis technology that releases hydrogen from chemical hydrogen storage materials is a method to produce hydrogen. Hydrogen storage has excellent development potential and is also one of the sources of large amounts of hydrogen. A sodium borohydride hydrogen production experiment was carried out based on steam hydrolysis technology. The system reaction tank is divided into a water-carrying bed and a catalyst bed. A mixed aqueous solution with a concentration of 1 wt% sodium hydroxide (NaOH) + 10 wt% sodium borohydride (NaBH4) was used for the hydrogen production reaction test. These experiments determined the appropriate aqueous solution and water vapor combination, and optimal parameters for hydrogen production. The hydrogen production catalyst powder, blend ratio, different steel ball ratios, and ball milling time at the steam hydrogen production end will all affect the powder's fineness and hydrogen production stability. Under catalyst temperature control, the by-products solidify at a specific temperature, which affects the gas passage and causes blockage. Increasing the hydrogen production in an aqueous solution requires a Co2+/Al2O3 catalyst, or a temperature control method to catalyze hydrogen production to obtain stable hydrogen production suitable for emergencies without hydrogen storage containers. This experiment built a hydrogen production system combined with a fuel cell for power generation testing. The test process and results indicate whether the aqueous solution and steam technology can be an effective solution when the hydrolysis hydrogen production technology is matched.

Photovoltaic-based energy system coupled with energy storage for all-day stable PEM electrolytic hydrogen production

Photovoltaic (PV) power generation coupled with proton exchange membrane (PEM) water electrolysis favors improving the solar energy utilization and producing green hydrogen. But few systems proposed focus on achieving all-day stable hydrogen production, which is important for the future large-scale hydrogen utilization. Herein, a PV-Battery-PEM water electrolysis system for hydrogen production was constructed. An energy management strategy (EMS) was proposed to achieve the goal of all-day stable hydrogen production, improve energy utilization efficiency and reduce light discard rate. The PV power generation system, battery system and PEM electrolyzer for hydrogen production system were first established by Matlab/Simulink platform. Then, the overall PV-Battery-PEM electrolyzer system for hydrogen production was constructed, and the effectiveness of EMS was verified. The energy efficiency of the system under different working conditions with and without battery for energy storage was analyzed. The results show that the proposed energy management strategy can meet the purpose of all-day stable hydrogen production. Under the same working conditions, the energy efficiency of the system with battery for energy storage increases by 2–4% compared with the system without battery for energy storage, which indicates that the addition of energy storage can improve the energy utilization and reduce the light discarding.

Photocatalytic degradation of PET coupled to green hydrogen generation using flexible Ni2P/TiO2/C nanofiber film catalysts

The increasing accumulation of waste plastics has a range of negative impacts on the land and marine environments. Solar-driven methods of converting waste into useful chemicals and green energy H2 are gaining attention due to their efficiency, stability and low cost. Here, flexible nickel phosphide/titanium dioxide/carbon nanofiber (Ni2P/TiO2/C NFs) film photocatalyst was prepared by electrospinning, heat treatment, hydrothermal method, and phosphate treatment. The obtained Ni2P/TiO2/C NFs presented a continuous homogeneous fibrous shape with TiO2 NPs incorporation into the carbon NFs and Ni2P NPs coating on the surface of the NFs. The film exhibited promising flexibility and excellent light absorption performance. As a result, the Ni2P/TiO2/C NFs film was utilized to reform polyethylene terephthalate (PET) into a variety of organic products and clean energy H2 under alkaline aqueous conditions. In addition, the flexible Ni2P/TiO2/C NFs film could be easily separated from the solution for recycling, and the stable hydrogen production performance was maintained after multiple cycles. This work applies an inexpensive and recyclable composite photocatalyst to the recycling of waste polyester, which is a crucial step towards the practical application of recyclable photocatalysts in resource recovery.

The exploration of hydrogen production promoting mechanism of Rhodobacter sphaeroides by expressing tetA under tetracycline stress

Photo-fermentative hydrogen production rate improving has been a key limiting link in the field of biological hydrogen production by photosynthetic bacterium (PSB) in recent years. In our previous study, apparent hydrogen production enhancement was observed in R. sphaeroides HY01 with tetA expressed under tetracycline (Tc), which attracted our interests. It was found that Tc-resistant strains always presented stable hydrogen production promotion on the maximum hydrogen production rate (Rm), which was approximately 30% with Tc addition. Figuring out the underlying connections between Tc resistance and hydrogen production of R. sphaeroides may provide new methods for obtaining engineered PSB with high hydrogen production performance. In this study, basing on experimental tests, hydrogen promotion of resistant strain was found to be Tc dose-dependent. Some relevant gene expression differences on hydrogen production of Rodobacter sphaeroides induced by the expression of TetA and the addition of Tc were also tested and discussed.

Back Cover: Multilayered Ceramic Membrane with Ion Conducting Thin Layer Induced by Interface Reaction for Stable Hydrogen Production (Angew. Chem. Int. Ed. 6/2023)

Multilayered ceramic membranes with ion-conducting dense thin layers are essential platforms for solid-state electrochemical devices, gas separation membranes, and sensors. In their Research Article (e202210485), Heqing Jiang et al. develop a new interface-reaction-induced reassembly approach for the direct fabrication of zirconia- or ceria-based dense thin layers rooted in multilayered ceramic membranes that show robust and practical performance for upgrading fossil-fuel-derived hydrogen.

Rücktitelbild: Multilayered Ceramic Membrane with Ion Conducting Thin Layer Induced by Interface Reaction for Stable Hydrogen Production (Angew. Chem. 6/2023)

Multilayered ceramic membranes with ion-conducting dense thin layers are essential platforms for solid-state electrochemical devices, gas separation membranes, and sensors. In their Research Article (e202210485), Heqing Jiang et al. develop a new interface-reaction-induced reassembly approach for the direct fabrication of zirconia- or ceria-based dense thin layers rooted in multilayered ceramic membranes that show robust and practical performance for upgrading fossil-fuel-derived hydrogen.

Recent progress in metal halide perovskite photocatalysts for hydrogen evolution

The basic design principles and recent progress in halide perovskite-based photocatalysts are summarized, aiming to achieve efficient and stable photocatalytic hydrogen production.

Ultralow Pt Catalyst Loading Prepared by the Electroreduction of a Supramolecular Assembly for the Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) from the electrocatalysis of water splitting is the most promising approach to producing green and renewable hydrogen energy for sustainable development. The precious metal platinum is the best electrocatalyst for HER. However, its scarcity and high cost still hinder the large-scale application. It is highly desirable to fabricate efficient Pt electrocatalysts with low Pt loading. Herein, we report an efficient ultralow Pt-loading HER catalyst, which was obtained by the electroreduction of a preprepared supramolecular self-assembly. Utilizing the strong hydrogen bonding formation ability of macrocyclic cucurbit[8]uril (CB[8]), a porous supramolecule (CB[8]-[PtCl6]) composed of [PtCl6]2– and CB[8] is obtained as the HER catalyst precursor. By the electroreduction of the as-prepared supramolecular compound, Pt nanoparticles (NPs) protected by CB[8] (CB[8]-Pt) exhibit high catalytic activity and excellent long-term stability toward HER with ultralow Pt loading. CB[8]-Pt with a Pt loading of only 1.2 μg/cm2 presents 23 times higher HER activity than commercial Pt/C. Moreover, CB[8]-Pt shows excellent stability under 10 000-cycle cyclic voltammetry (CV) and at least 120 h for chronopotentiometry at 10 mA/cm2 in 0.5 M H2SO4, which greatly outperforms commercial Pt/C. This work provides a strategy for the rational design of ultralow-loading Pt catalysts with good activity and stability for hydrogen production.

Air‐condition process for scalable fabrication of CdS/ZnS 1D/2D heterojunctions toward efficient and stable photocatalytic hydrogen production

AbstractWe report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions (i.e., room temperature and atmospheric pressure) in which ZnS nanoparticles are anchored on the surface of CdS nanosheets. The as‐formed heterojunctions exhibit a significantly enhanced photocatalytic H2 evolution rate of 14.02 mmol h−1 g−1 when irradiated with visible light, which is ~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles, respectively, and superior to most of the CdS‐based photocatalysts reported to date. Furthermore, they provide robust photocatalytic performance with demonstratable stability over 58 h, indicating their potential for practical applications. The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single‐crystalline CdS nanosheets. In addition, first‐principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type‐II and Z‐scheme mixed heterojunctions, which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.

Multilayered Ceramic Membrane with Ion Conducting Thin Layer Induced by Interface Reaction for Stable Hydrogen Production

AbstractConventional methods for fabricating multilayered ceramic membranes with ion conducting dense thin layers are often cumbersome, costly, and limited by poor adhesion between layers. Inspired by the architectural structure of the rooted grasses in soil, here, we report an interface‐reaction‐induced reassembly approach for the direct fabrication of Ce0.9Gd0.1O2−δ (CGO) thin layers rooted in the parent multilayered ceramic membranes by only one firing step. The CGO dense layers are very thin, and adhered strongly to the parent support layer, ensuring low ionic transport resistance and structural integrity of the multilayered membranes. When using as an oxygen permeable membrane for upgrading fossil‐fuel‐derived hydrogen, it shows very long durability in harsh conditions containing H2O, CH4, H2, CO2 and H2S. Furthermore, our approach is highly scalable and applicable to a wide variety of ion conducting thin layers, including Y0.08Zr0.92O2−δ, Ce0.9Sm0.1O2−δ and Ce0.9Pr0.1O2−δ.

Multilayered Ceramic Membrane with Ion Conducting Thin Layer Induced by Interface Reaction for Stable Hydrogen Production.

Conventional methods for fabricating multilayered ceramic membranes with ion conducting dense thin layers are often cumbersome, costly, and limited by poor adhesion between layers. Inspired by the architectural structure of the rooted grasses in soil, here, we report an interface-reaction-induced reassembly approach for the direct fabrication of Ce0.9 Gd0.1 O2-δ (CGO) thin layers rooted in the parent multilayered ceramic membranes by only one firing step. The CGO dense layers are very thin, and adhered strongly to the parent support layer, ensuring low ionic transport resistance and structural integrity of the multilayered membranes. When using as an oxygen permeable membrane for upgrading fossil-fuel-derived hydrogen, it shows very long durability in harsh conditions containing H2 O, CH4 , H2 , CO2 and H2 S. Furthermore, our approach is highly scalable and applicable to a wide variety of ion conducting thin layers, including Y0.08 Zr0.92 O2-δ , Ce0.9 Sm0.1 O2-δ and Ce0.9 Pr0.1 O2-δ .

A noble metal-free candle soot derived carbon electrocatalyst for simultaneous H2 generation and wastewater treatment

Electrocatalytic water splitting to produce green hydrogen is a promising approach for clean energy generation. However, the commercial aspect of this approach is limited due to catalysts cost and feedstock. Thus design of an inexpensive and noble metal-free (Pt, Rh, Ir etc.) catalyst is desirable. Moreover, wastewater as a feedstock for hydrogen generation is not explored to its full potential for green hydrogen generation, which otherwise is also a problem to be managed especially in developing countries. In the present work, we have investigated an inexpensive catalyst i.e. candle soot-derived carbon as an electrocatalyst for H2 generation from textile wastewater utilizing methylene blue as a model pollutant. The carbon catalyst is synthesized from the candle soot and is characterized for its structural and morphological properties. Carbon soot coated onto the nickel foam (CS@NF) proves as an efficient hydrogen evolution catalyst due to its excellent electrical conductivity and large active surface area. CS2.5@NF (with the loading of 2.5 mg cm−2) shows an overpotential and Tafel slope of 117 mV and 43.85 mV/dec, respectively in an acidic medium containing textile pollutants. Under optimal condition, ∼62% degradation is achieved within ∼90 min, along with the stable hydrogen production of ∼0.158 mmol per hour. These preliminary findings demonstrate the potential usage of an inexpensive non-noble metal free catalyst for simultaneous wastewater treatment as well as hydrogen generation.

Improved hydrogen production performance of Ni–Al2O3/CaO–CaZrO3 composite catalyst for CO2 sorption enhanced CH4/H2O reforming

Bifunctional composite catalysts are very intrigued to produce hydrogen via CO2 sorption enhanced CH4/H2O reforming. However, their hydrogen production performance declined over multiple cycles, owing to the structure collapse and the sintering of active component under high-temperature regeneration. This work reported the facile synthesis of long-lasting Ni–Al2O3/CaO–CaZrO3 composite catalysts with less inert components (36 wt%) for stable hydrogen production over the multiple cycles of CO2 sorption enhanced CH4/H2O reforming. The effects of reaction and regeneration temperature on the hydrogen production performance of Ni–Al2O3/CaO–CaZrO3 were explored. Ni–Al2O3/CaO–CaZrO3 demonstrated high activity and stability while fixing reaction temperature as 600 °C and regeneration temperature as 750 °C. Of particular importance, H2 concentration was 98 vol% even after 10 hydrogen production cycles due to the inert component CaZrO3 having a cross-linked structure. The distribution of CaZrO3 in the composite as a coral-like structure inhibited the sintering of CaO through high Taman temperature and physical separation. Moreover, it provided the skeleton support and pore volume for the repeated expansion and contraction process of CaO to CaCO3 during the cycling process. Finally, the sintering of Ni slowed down in appropriate regeneration temperature to maintain the structure of the composite catalyst, which further improved the catalyst's stability over multiple cycles.

Bifunctional g-C3N4/carbon nanotubes/WO3 ternary nanohybrids for photocatalytic energy and environmental applications

Ternary nanohybrids based on mesoporous graphitic carbon nitride (g-C3N4) were synthesized and presented for developing stable and efficient Hydrogen (H2) production system. Based on photocatalytic activity, optimization was performed in three different stages to develop carbon nanotubes (CNTs) and WO3 loaded g-C3N4 (CWG-3). Initially, the effect of exfoliation was investigated, and a maximum specific surface area of 100.77 m2/g was achieved. 2D-2D interface between WO3 and g-C3N4 was targeted and achieved, to construct a highly efficient direct Z-scheme heterojunction. Optimized binary composite holds the enhanced activity of about 2.6 folds of H2 generation rates than the thermally exfoliated g-C3N4. Further, CNT loading towards binary composite in an optimized weight ratio enhances the activity by 6.86 folds than the pristine g-C3N4. Notably, optimized ternary nanohybrid generates 15,918 μmol h−1. g−1cat of molecular H2, under natural solar light irradiation with 5 vol% TEOA as a sacrificial agent. Constructive enhancements deliver remarkable H2 production and dye degradation activities. Results evident that, the same system can be useful for pilot-scale energy generation and other photocatalytic applications as well.

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.

Mn-doped nickel–iron phosphide heterointerface nanoflowers for efficient alkaline freshwater/seawater splitting at high current densities

To realize highly efficient and stable hydrogen production at high current densities, more efforts are devoted to developing outstanding water-splitting electrocatalysts. Herein, through a facile hydrothermal-phosphorization method, Mn-doped Ni2P/Fe2P was rationally designed and prepared as a high-performance bifunctional electrocatalyst for alkaline freshwater/seawater splitting. In alkaline seawater (freshwater) electrolyte, it merely needs low overpotentials of 358 (335) and 470 (405) mV to reach 1000 mA cm−2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. This electrocatalyst also shows excellent stability even at a high OER current density of 500 mA cm−2 for 200 h. Regarding the alkaline overall seawater splitting, Mn-doped Ni2P/Fe2P presents a low cell voltage of 2.02 V at 500 mA cm−2 and outstanding stability for 120 h at the same current. The X-ray absorption fine structure (XAFS) experimental analysis verifies that the Mn doping and Ni2P/Fe2P heterointerfaces can efficiently optimize the electrocatalyst’s electronic structure, leading to the improved intrinsic OER and HER activities. Meanwhile, the 3D nanoflower structure provides abundant exposed active sites, and the Mn doping and heterointerfaces can create more active sites. Besides, the high corrosion resistance resulting from nickel-iron phosphides makes the electrocatalyst become a good candidate for seawater splitting. This study provides a simple path to fabricate highly active and robust non-noble electrocatalysts for freshwater/seawater splitting at high current densities.

Atomically Interfacial Engineering on Molybdenum Nitride Quantum Dots Decorated N-doped Graphene for High-Rate and Stable Alkaline Hydrogen Production.

The development of low-cost, high-efficiency, and stable electrocatalysts for hydrogen evolution reaction (HER) under alkaline conditions is a key challenge in water electrolysis. Here, an interfacial engineering strategy that is capable of simultaneously regulating nanoscale structure, electronic structure, and interfacial structure of Mo2 N quantum dots decorated on conductive N-doped graphene via codoping single-atom Al and O (denoted as AlO@Mo2 N-NrGO) is reported. The conversion of Anderson polyoxometalates anion cluster ([AlMo6 O24 H6 ]3- , denoted as AlMo6) to Mo2 N quantum dots not only result in the generation of more exposed active sites but also in situ codoping atomically dispersed Al and O, that can fine-tune the electronic structure of Mo2 N. It is also identified that the surface reconstruction of AlOH hydrates in AlO@Mo2 N quantum dots plays an essential role in enhancing hydrophilicity and lowering the energy barriers for water dissociation and hydrogen desorption, resulting in a remarkable alkaline HER performance, even better than the commercial 20% Pt/C. Moreover, the strong interfacial interaction (MoN bonds) between AlO@Mo2 N and N-doped graphene can significantly improve electron transfer efficiency and interfacial stability. As a result, outstanding stability over 300 h at a current density higher than 100 mA cm-2 is achieved, demonstrating great potential for the practical application of this catalyst.

Stable p-block metals electronic perturbation in PtM@CNT (M=Ga, In, Pb and Bi) for acidic seawater hydrogen production at commercial current densities

Achieving acidic seawater hydrogen production under commercial current densities remains a challenge. We present here a novel strategy through strong metal-support interaction (SMSI) and Pt-p-block alloys (PtM@CNT, M = Ga, In, Pb, and Bi) to construct a stable electronic perturbation and achieve acidic seawater hydrogen evolution performance at commercial current densities for the first time. SMSI stabilizes electronic perturbation and promotes durability up to 360 h. The optimized Pt61Ga39 @CNT exhibits an overpotential of 18 mV at 10 mA cm−2 in 0.5 M H2SO4 and maintains 360 h stability at 500 mA cm−2 in acidic seawater. Density functional theory (DFT) calculation reveals that the optimized d-band center of Pt and ΔGH* increase the catalytic activity, and the higher vacancy formation energy enhances the durability. Overall, this discovery not only first achieves stable acidic seawater hydrogen production under commercial current densities, but also opens a new opportunity to explore catalytic applications of p-block alloys and SMSI stabilized electronic perturbation.

Dry reforming of methane over Ni/ZrO2 and NiCu/ZrO2 thin layer nanocatalysts in a microchannel reactor: The effect of coating time

AbstractIn this study, the performance of thin film Ni/ZrO2 and NiCu/ZrO2 catalysts in a microchannel reactor in the dry methane reforming reaction (DRM) is investigated. Thin film nanocatalysts are prepared by the physical vapor deposition (PVD) method. GIXRD, FESEM‐Cross, FESEM‐Surface, and EDX analyzes are used to evaluate the properties of thin film nanostructures. The results show that in addition to the addition of copper as a promoter, a change in the coating time causes a change in the formation of the thin layer and the growth mechanism of the layers. Reactor tests are evaluated at temperatures ranging from 700°C to 800°C, at P = 1 atm, with a CH4:CO2 ratio of 1. Results of this study are compared with two other studies in fixed bed reactors that show the microchannel reactor has better performance. The presence of copper on Ni/ZrO2 could have significant effects on the stability of hydrogen production and the reduction of carbon deposition. Thin film Ni/ZrO2 catalyst with 2 min coating time and NiCu/ZrO2 catalyst with NiCu weight ratio of 4: 1 with 1 min coating time at 800°C show the best performance in terms of hydrogen production and H2/CO ratio (1.43 for a sample of Ni/ZrO2 and 1.68 for a sample of NiCu/ZrO2).