Improved Hydrogen Evolution Research Articles

Insights into the Effect of Sulfur Incorporation into Tungsten Diphosphide for Improved Hydrogen Evolution Reaction.

Exploring the highly active and stable nonprecious metal electrocatalysts is particularly important for the advancement of water electrolysis, whereas it remains a challenge to efficiently improve the intrinsic electrocatalytic activity. Herein, we reasonably constructed a self-supporting nanosheet array material with sulfur incorporated into WP2. Because of the tunability of electronic configuration and the formation of partial metal phase sulfides, the optimized catalyst exhibits a low overpotential of 115 mV at 10 mA cm-2, along with superb durability over 24 h in acidic media. Furthermore, theoretical calculations reveal that sulfur substitution effectively manipulates the local electronic configuration of WP2, which reduces the interaction between the catalyst surface and hydrogen atoms, thus improving the intrinsic activity of the hydrogen evolution reaction. This work provides valuable insight into the rational fabrication of highly efficient flexible electrode materials based on resourceful electrocatalysts for electrochemical water splitting.

Nanomaterials For Hydrogen Generation: A Review

Hydrogen is proving its potential as most appealing and eco friendly energy fuels. Theorganic reforming based nano-sized composites and nanocatalyst for photocatalytic water splitting applications are attracting growing interest in the prospect of hydrogen generation from solar energy with minimal environmental impact. Because of the higher surface area and sizedependent features, such as increased absorption coefficient,reduced carrier-scattering rate and increased band-gap energy, the nano- semiconductors have potential advantages in PEC applications when compared to bulk materials. Despite recent research in producing materials having high specific photoactivity, the conversion efficiencies from solar-to-hydrogen are still far from achieving the basic requirements for actual solar applications, according to a literature review. The paper begins by providing an overview of the conventional hydrogen generation techniques. This paper also examines current advances and challenges in water splitting methods based on Photo Electro Chemistry based nanomaterials and various ways for improving hydrogen evolution.

A new strategy for the fabrication of covalent organic framework-metal-organic framework hybrids via in-situ functionalization of ligands for improved hydrogen evolution reaction activity

The development of novel porous materials have attracted significant attention owing to its possible application in several fields. In this study, we designed a novel covalent organic framework-metal-organic framework (COF-MOF) material through an in-situ ligand self-assembly method. The in-situ modified ligands not only act as nucleation sites to form Ti-MOF, but also as a channel to rapidly transfer photogenerated electrons without introducing additional chemical bonds. The photocatalytic hydrogen production rate achieved over B-CTF-Ti-MOF(1:1) was 1975 µmol·g−1·h−1 with an apparent quantum efficiency of 4.76%, which is 11.8 times higher than that of the pure CTF-1. In addition, compared with the sample prepared by separating the ligands (CTF-1/Ti-MOF), B-CTF-Ti-MOF shows excellent activity and stability. Finally, a reasonable photocatalytic mechanism was proposed using the results of electrochemical tests and spectral analyses. This study provides a universal method for the construction of highly efficient and stable COF/MOF materials with excellent properties.

Fe-doped NiCo2S4 catalyst derived from ZIF – 67 towards efficient hydrogen evolution reaction

The development of economical, efficient and stable non-noble metal catalysts plays a key role in electrocatalytic hydrogen evolution. NiCo 2 S 4 has been proved to be an efficient non-noble catalyst, to further improve its electrocatalytic performance is a meaningful work. In this paper, the effects of Fe doping on electrochemical performance of NiCo 2 S 4 is investigated. The Fe-doped NiCo 2 S 4 catalyst is prepared by a facile solvothermal method with metal-organic-framework (MOF, ZIF-67) as template, and it exhibits an improved hydrogen evolution reaction (HER) performance with an overpotential of 181 mV at 10 mA cm −2 , a Tafel slope of 125 mV dec −1 compared with that of NiCo 2 S 4 (252 mV overpotential and 149 mV dec −1 Tafel slope). The combination of improved conductivity, mesopores architecture retained with the ZIF-67 template, which result the reduced internal resistance, enhanced charge transportation as well as large electrochemical double-layer capacitance. This work provides an effective and synergistic strategy for fabricating NiCo 2 S 4 -based catalysts toward electrochemical water splitting. • Fe-doped NiCo 2 S 4 catalyst was synthesized by using ZIF-67 as a template. • The conductivity of NiCo 2 S 4 is increased by Fe doping. • Mesopores architecture of the Fe-doped NiCo 2 S 4 is retained with the template. • The Fe-doped NiCo 2 S 4 catalyst presents an improved HER activity and stability.

Improving Hydrogen Evolution Reaction with a Hydrogenase-Like Nanozyme

Improving Hydrogen Evolution Reaction with a Hydrogenase-Like Nanozyme

Extreme Environmental Thermal Shock Induced Dislocation‐Rich Pt Nanoparticles Boosting Hydrogen Evolution Reaction (Adv. Mater. 2/2022)

Nanocrystal Dislocations Inducing dislocations is an efficient approach to generate strain effects in nanomaterials. In article number 2106973, Yanan Chen and co-workers report a non-equilibrium high-temperature thermal-shock method (HTS) to induce dislocations in nanocrystals by using liquid nitrogen. The dislocations induced by thermal and structural stress are frozen in nanoparticles. The extreme environmental HTS can introduce dislocations in Pt nanoparticles and improve hydrogen evolution reaction performance.

Integrating trace amounts of Pd nanoparticles into Mo3N2 nanobelts for an improved hydrogen evolution reaction.

Significant efforts have been directed towards the use of transition metal nitrides as electrocatalysts for the hydrogen evolution reaction (HER). Molybdenum nitride, despite its potential for scalable production, suffers from the bottleneck of poor catalytic activity. Furthermore the kinetics of the water dissociation process ought to be improved for enhancing its potential. Here, we report a facile method for the incorporation of a trace amount of Pd nanoparticles into Mo3N2 nanobelts (0.75 Pd/Mo3N2) for an enhanced HER in both acidic and alkaline solutions. When employed for the HER, the 0.75 wt% Pd/Mo3N2 nanobelt delivers excellent catalytic activity with overpotentials of 45 and 65 mV in 0.5 M H2SO4 and 1 M KOH at a current density of 10 mA cm-2. As-prepared 0.75 wt% Pd/Mo3N2 displays a smaller Tafel slope and offers substantial stability in both acidic and alkaline media under the same operating conditions. The improved performance of the as-prepared 0.75 wt% Pd/Mo3N2 points to fast charge transfer, higher electrical conductivity and synergistic effects between Pd and Mo. This work displays a direct method for reducing the use and cost associated with the use of platinum-group metals while also delivering superior HER catalytic performance.

Electrocatalytic activity for proton reduction by a covalent non-metal graphene-fullerene hybrid.

A non-metal covalent hybrid of fullerene and graphene was synthesized in one step via fluorographene chemistry. Its electrocatalytic performance for the hydrogen evolution reaction and durability was ascribed to intrahybrid charge-transfer phenomena, exploiting the electron-accepting properties of C60 and the high conductivity and large surface area of graphene.

Metal-organic framework (MOF)-derived plate-shaped CoS1.097 nanoparticles for an improved hydrogen evolution reaction.

Metal-organic framework (MOF)-derived transition metal sulfides are viewed as reliable, cost-effective, and alternative hydrogen evolution reaction (HER)-efficient electrocatalysts. They have been used to replace platinum (and their alloys) for production of renewable energy carriers such as hydrogen. Progress towards development of non-precious transition-metal sulfides through different synthetic routes to obtain unique morphological nanostructures with enhanced HER activity is challenging. We introduced a transition-metal sulfide, cobalt sulfide (CoS1.097), derived from a cobalt MOF [Co-BPY-DDE] by following facile, one-step solvothermal sulfurization. By varying the sulfurization temperature (from 140 °C to 180 °C) during the solvothermal method, three cobalt-sulfide products were obtained: CoS1.097-140, CoS1.097-160, and CoS1.097-180, respectively. Temperature variation had a vital role in optimizing the HER activity of the electrocatalyst. Besides, notable plate-shaped cobalt sulfide nanoparticles (CoS1.097-160) required overpotential of 163 mV to deliver a current density of 10 mA cm-2 with a low Tafel slope of 53 mV dec-1, thereby demonstrating faster reaction kinetics during the evolution of molecular hydrogen. Furthermore, 25 h of long-term stability of the electrocatalyst reflected its practical applicability in acidic media. CoS1.097-160 had uniform plate-shaped morphology and large electrochemical active surface area, which contributed to enhanced electrochemical performance through water electrolysis.

Robust direct Z-scheme exciton transfer dynamics by architecting 3D BiOI MF-supported non-stoichiometric Cu0.75In0.25S NC nanocomposite for co-catalyst-free photocatalytic hydrogen evolution.

Designing promising photocatalytic systems with wide photon absorption and better exciton separation ability is a cutting-edge technology for enhanced solar-light-driven hydrogen production. In this context, non-stoichiometric Cu0.75In0.25S nanocrystals (CIS NCs) coupled with three-dimensional (3D) BiOI micro-flowers (BOI MFs) were synthesized through an ultra-sonication strategy forming a CIS–BOI heterojunction, which was well supported by XRD, photocurrent, XPS and Mott–Schottky analyses. Further, the co-catalyst-free CIS–BOI binary hybrid shows improved hydrogen evolution, i.e., 588.72 μmol h−1, which is 3.2 times greater than the pristine CIS NC (183.97 μmol h−1). Additionally, the binary composite confers an apparent conversion efficiency (ACE) of 9.44% (8.90 × 1016 number of H2 molecule per sec), which is extensively attributed to the robust charge carrier separation and transfer efficiency via the direct Z-scheme mechanism (proved through superoxide and H2 evolution activity). Moreover, the broad photon absorption range and productive exciton separation over the CIS–BOI composite are substantially justified by UV-Vis DRS, PL, EIS and photocurrent measurements.

Hollow MoS2-supported MAPbI3composites for effective photocatalytic hydrogen evolution

A facile and effective electrostatic adsorption method was developed to fabricate H-MoS2/MAPbI3composites, which improved hydrogen evolution activity and stability.

The highly improved hydrogen evolution performance of a 0D/0D MoP-modified P-doped Mn0.5Cd0.5S photocatalyst.

In this paper, we present a MoP/P-Mn0.5Cd0.5S photocatalytic material (PMOMCS-Px). A novel catalyst can efficiently split water into hydrogen without precious metals. In the sacrificial agent environment, the HER (hydrogen evolution rate) of PMOMCS-P5 was 4368.25 μmol g-1 h-1 which was 11.4 times greater than the HER of Mn0.5Cd0.5S (383.19 μmol g-1 h-1), and its hydrogen production performance was better than that of Pt/Mn0.5Cd0.5S (2.0 wt% Pt). Furthermore, the hydrogen evolution performance of PMOMCS-P5 under pure water conditions was also examined, and the HER of PMOMCS-P5 was 209.76 μmol g-1 h-1, which was 20.4 times that of Mn0.5Cd0.5S (10.29 μmol g-1 h-1). Its characterization proved that the introduction of the co-catalyst MoP and P doping inhibited the recombination of e- and h+, enhanced the reduction capacity, and reduced the hydrogen precipitation reaction overpotential of PMOMCS-Px, thus enhancing the hydrogen production performance of PMOMCS-Px. Therefore, an efficient and economical photocatalyst was prepared.

Improved hydrogen evolution performance by engineering bimetallic AuPd loaded on amino and nitrogen functionalized mesoporous hollow carbon spheres.

A highly efficient heterogeneous catalyst was synthesized by delicate engineering of NH2-functionalized and N-doped hollow mesoporous carbon spheres (NH2–N-HMCS), which was used for supporting AuPd alloy nanoparticles with ultrafine size and good dispersion (denoted as AuPd/NH2–N-HMCS). Without using any additives, the prepared AuPd/NH2–N-HMCS catalytic formic acid dehydrogenation possesses superior catalytic activity with an initial turnover frequency value of 7747 mol H2 per mol catalyst per h at 298 K. The excellent performance of AuPd/NH2–N-HMCS derives from the unique hollow mesoporous structure, the small particle sizes and high dispersion of AuPd nanoparticles and the modified Pd electronic structure in the AuPd/NH2–N-HMCS composite, as well as the synergistic effect of the modified support.

Amorphous/Crystalline Heterophase Ruthenium Nanosheets for pH‐Universal Hydrogen Evolution

To design and synthesize heterophase noble-metal materials is of crucial importance owing to their unique structure and apparent properties. Ruthenium (Ru) is one of the most active candidates for hydrogen evolution reaction because of its low price compared with other precious metals, which is favorable for industrial hydrogen cycle operation. In this study, free-standing amorphous/crystalline Ru nanosheets are facilely synthesized through a controlled annealing method. Charge redistribution occurs at the phase interface because of the work function difference between amorphous and crystalline domains. The resulting structure and property are conductive to the adsorption and dissociation of water molecules, associated with optimized hydrogen interaction and enhanced binding between Ru atoms. Accordingly, electrochemical measurements demonstrate that the amorphous/crystalline heterophase Ru exhibits improved hydrogen evolution efficiency as compared with pure amorphous Ru and pure crystalline Ru, at pH-universal conditions. Specifically, only 16.7mV overpotential is required to reach 10mA cm-2 in 1.0 m KOH. Meanwhile, the heterophase structure displays a higher stability during operation than pure amorphous and crystalline structures. This study demonstrates the importance of phase engineering, broadens the Ru-based material family, and provides more insights for developing efficient metal materials.

Low temperature activation of inert hexagonal boron nitride for metal deposition and single atom catalysis

Hexagonal boron nitride (hBN) has long been considered chemically inert due to its wide bandgap and robust covalent bonds. Its inertness hinders hBN from functionalization for energy conversion applications. A question arising is whether it is possible to make hBN chemically reactive. Here, we report cryomilling in liquid N2, as an effective strategy to activate the chemical reactivity of hBN by engineering different vacancies to produce defective-BN (d-BN). The local reactivity of the vacancies is probed by photoluminescence (PL) emissions and electron spin resonance spectroscopy (ESR). Density functional theory calculations reveal that the formation of different vacancies with/without oxygen cause the creation of mid-gap states that are responsible for the PL emissions in the visible region. These vacancies also generate localized free radicals which are both theoretically and experimentally confirmed by spin density calculations and ESR. Due to the vacancy induced free radicals and Fermi level shifts, d-BN can be controllably functionalized with single metal atoms by the spontaneous reduction of metal cations; mono-metallic or bi-metallic clusters can also be effectively reduced. As a proof of concept, the surface-bound metal nanostructures, especially substrate confined single metal atoms, exhibit improved hydrogen evolution catalytic performance, and can be further used for sensing, and quantum information.

Composition adjustment of PtCoCu alloy assemblies towards improved hydrogen evolution and methanol oxidation reaction

Binary PtCo, PtCu and ternary PtCoCu alloys with different surface element distributions were prepared to study the effect of composition on electrocatalytic hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). A one-pot method was used to synthesize self-assembled alloy nanocrystals in one step. By adjusting the composition of synthesized alloys, their properties were optimized. The changes of morphology and property of the alloys after adding Cu were discussed. The HER and MOR properties of alloys were affected by the composition. Especially, the ternary alloy revealed better properties than that of the binary alloy. The starting potential of PtCoCu alloy in HER reaction under visible light is 14 mV and the overpotential under 10 mA cm−1 is 44 mV, which revealed excellent cycle stability. The current density at 0.7 V for MOR reaction can reach 4.2 mA cm−1. This is ascribed to the composition of alloy. Cu in alloys resulted in plasma-induced effective electron transfer. This result provides a feasible strategy for the design of effective multifunctional electrocatalysts.

Doping engineering: Highly improving hydrogen evolution reaction performance of monolayer SnSe

By using the first-principles approach, we explore the hydrogen evolution reaction (HER) performance of SnSe monolayer. It is found that the SnSe monolayer with or without intrinsic defects is not good HER catalyst. By doping eighteen different elements at Sn or Se sites of the SnSe monolayer, we find that the elements P and In can effectively reduce the free energies of hydrogen (H) adsorption (ΔG) to −0.1 eV and 0.21 eV, much lower than 1.45 eV of perfect monolayer SnSe. This is attributed to great dispersion of electronic density of states of absorbed hydrogen atom having small interactions with doping elements. However, strong hybridizations between H and doping elements (K and Te) increase the ΔG values of doping systems (ΔG = 2.84 eV and ΔG = 1.77 eV).

Pollen-like self-supported FeIr alloy for improved hydrogen evolution reaction in acid electrolyte

Ir is recognized as efficient catalyst for hydrogen evolution reaction (HER). The high price, however, has hindered its application in the production of hydrogen. In this work, we prepared the self-supported FeIr alloy nanoparticles, taking advantage of solid-state synthesis method. The as-prepared FeIr alloy possesses a novel morphology of pollen, which is consist of smaller FeIr nanoparticles. DFT calculations reveal that the change of the free Gibbs for Ir is negative after the adsorption of active H, while it is positive for the case of Fe. Thus, the alloying of Fe and Ir not only effectively reduces the cost, but also can achieve more adequate adsorption of active H species. Benefitting from this, the as-prepared FeIr alloy nanoparticle exhibits superior HER performance with an overpotential of 19 mV at a current density of 10 mV/cm2 and a Tafel slope of 32 mV/dec, when tested in 0.5 M H2SO4, better than pure Ir and Pt/C. This work paves the way to the exploration of efficient alloy electrocatalysts for HER.

Boosting hydrogen evolution electrocatalysis through defect engineering: A strategy of heat and cool shock

Developing new strategy to further improve hydrogen evolution reaction (HER) performance of transition metal-based electrocatalysts is of high significance to accelerate commercial application of hydrogen energy. Here, HER activity is significantly enhanced through introducing crystal defects. The combined methods of heat and cool shock calcination, mask fiber templates as both reducing agent and carbon source were applied to synthesize microtube-like electrocatalysts composed of cross-linked carbon sheets and ultrafine Ni nanoparticles. The extensive active sites (edges, corners, steps, jaggies and strain) on the surface of Ni nanoparticles caused by grain surface, twin boundaries and stacking faults could synergically accelerate HER activity by optimizing adsorption capability of electrocatalysts and exposing atoms with high surface energy. Meanwhile, the defect-rich Ni nanoparticles wrapped by few-layer graphene are uniformly fixed on the conductive carbon network, which provides abundant diffusion channels for H2 and electrolyte, as well as effectively prevents Ni nanoparticles aggregation and avoids Ni grains being peeled off during long-term HER operation. As expected, the as-prepared electrocatalyst exhibits prominently improved electrocatalytic activity and admirable stability for HER. This work provides some innovatively technical insight in new-type catalysts development and defects engineering.

Thermodynamic and kinetics of hydrogen photoproduction enhancement by concentrated sunlight with CO2 photoreduction by heterojunction photocatalysts

For achieving water splitting into hydrogen under sunlight for practical applications, the high efficiencies of the photoreduction of CO2 over TiO2/Fe3O4 photocatalysts combined with hydrogenation of water splitting over Pt/TiO2 were investigated by practical concentrated solar energy compared with Hg lamp and Xe lamp. Based on AI analysis on the influence factors, the key parameters for TOC concentration were photocatalysts, Na2CO3 concentration and radiation intensity while the key parameters for hydrogen production were photocatalysts, radiation intensity, and TOC concentration. Accordingly, the mechanism of concentrated sunlight effects has been discussed from the view of thermodynamics and kinetics. The concentrated sunlight provides a simultaneous supply of sufficient electron–hole pairs and thermal energy. Water to hydrogen and CO2 reduction are both enhanced in concentrated sunlight due to endothermal reactions. Doping changes the internal electric field of p-n junction of in different possible ways, and thus composite photocatalysts with favorable formation of p-n junctions would enhance the charge separation by internal electric field. Moreover, photocatalysts are beneficial for providing more excited electrons at a time for achieving CO2 photoreduction at the surface region of the particles with higher density of radiation by concentrated solar energy. Subsequently, products from CO2 photoreduction, acting as sacrificial electron donors, improved hydrogen evolution in solar-mediated water splitting for prohibiting reverse reactions.