High HER Research Articles

Metal–organic framework derived nitrogen-doped carbon-RhNi alloys anchored on graphene for highly efficient hydrogen evolution reaction

Nitrogen-doped carbon-RhNi alloy nanoparticles anchored on reduced graphene oxide nanosheet hybrid structure (NC-RhNi/rGO) exhibit high HER performance.

A high performance and low cost poly(dibenzothiophene-S,S-dioxide)@TiO2 composite with hydrogen evolution rate up to 51.5 mmol h−1 g−1

PDBTSO@TiO2-10 exhibited an extremely high HER of 51.5 mmol h−1 g−1 under visible light illumination.

Amorphous FeOx (x = 1, 1.5) coated Cu3P nanosheets with bamboo leaves-like morphology induced by solvent molecule adsorption for highly active HER catalysts

Bamboo leaves-like g-FeOx–Cu3P@Cu nanosheets induced by solvent molecule adsorption leading to high HER activity.

Engineering MoS2 nanostructures from various MoO3 precursors towards hydrogen evolution reaction

MoS2, MoO2–MoS2-B and MoO2–MoS2-R nanoflowers were prepared using α-MoO3 particles, α-MoO3 nanobelts and h-MoO3 microrods, respectively; larger exposure of Mo–S and lower amounts of Mo–O were responsible for the higher HER performance.

Direct Growth of Highly Strained Pt Islands on Branched Ni Nanoparticles for Improved Hydrogen Evolution Reaction Activity.

The direct growth of Pt islands on lattice mismatched Ni nanoparticles is a major synthetic challenge and a promising strategy to create highly strained Pt atoms for electrocatalysis. By using very mild reaction conditions, Pt islands with tunable strain were formed directly on Ni branched particles. The highly strained 1.9 nm Pt-island on branched Ni nanoparticles exhibited high specific activity and the highest mass activity for hydrogen evolution (HER) in a pH 13 electrolyte. These results show the ability to synthetically tune the size of the Pt islands to control the strain to give higher HER activity.

Hydrogen and oxygen evolution reactions of molybdenum disulfide synthesized by hydrothermal and plasma method

Molybdenum disulfide (MoS2) is synthesized via a facile hydrothermal method and modified by using ambient solution plasma for bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). The synthesized MoS2 exhibits low overpotential of −0.06 V and 1.22 V at 10 mA cm−2 with small Tafel slope (33 and 62 mV dec−1) for HER and OER, respectively, which it is comparable to platinum (30 and 172 mV dec−1). The high HER and OER performance attributes to increased electrochemical active surface area by twice and reduced impedance by almost twice compared to precursor MoS2 which has no plasma treatment, indicating that the plasma treatment introduces catalytic active surface area, which is a key factor for the efficient HER and OER and provides a positive effect on HER and OER performance.

Ni0-rich Ni/NiO nanocrystals for efficient water-to‑hydrogen conversion via urea electro-oxidation

It is highly desired to develop low-cost and effective non-precious metal based electrocatalysts for water-to‑hydrogen conversion assisted by urea electro-oxidation reaction. In this work, Ni0-rich Ni/NiO nanocrystals were facilely synthesized on the surface of acid-treated nickel foam via thermal annealing in Ar/H2 (denoted as NF@Acid-H2). The three-dimensional free-standing NF@Acid-H2 electrode exhibited high HER and UOR activities at 156 mV and at 1.33 V to reach the current density of 10 mA/cm2, respectively. The urea electrolyzer needed a cell voltage of 1.49 V to deliver the current density of 10 mA/cm2, and could continuously generate H2 for 20 h with negligible activity loss. Systematic study revealed that the presence of Ni0 played a significant role to improve both HER and UOR performance. In particular, the Ni0-rich Ni/NiO exhibited better catalytic performance than that of Ni0-less counterpart. This work proved that the high urea electrolysis performance was dependent on the rational design of non-precious metal electrocatalysts with controllable compositions and hierarchical nanostructures.

Molybdenum disulfide coated nickel-cobalt sulfide with nickel phosphide loading to build hollow core-shell structure for highly efficient photocatalytic hydrogen evolution

A hollow spherical NiCo2S4 photocatalytic material was prepared with a high HER activity in the dye sensitization system. Then the hollow spherical NiCo2S4 was coated by the sheet-shaped 2D MoS2. Through the band gap adjustment, a type-II heterostructure is constructed to move the photogenerated electrons to the outer layer, and part of photogenerated holes migrate to the inner layer, which successfully reduces the degradation rate of the dye sensitizer for slowing down the decay of H2 evolution rate in the dye sensitization system. In addition, Ni2P was used to enrich photogenerated electrons on the outer layer of MoS2 thereby achieving more efficient hydrogen production. The photocatalytic materials were characterized by XRD, SEM, TEM, XPS, UV–vis DRS and N2 Isothermal adsorption experiments. The transfer mechanism of photogenerated carriers was studied by PL, photoelectrochemical tests, and hydroxyl radical capture experiments.

A unique amorphous cobalt-phosphide-boride bifunctional electrocatalyst for enhanced alkaline water-splitting

A unique cobalt-phosphide-boride (Co-P-B) catalyst was synthesized via simple chemical-reduction route. The obtained catalyst was amorphous in nature, resembling the spherical morphology of Co-B nanoparticles. X-ray photoelectron spectroscopy revealed that B loses electrons to Co while P gains electrons from Co. This unique electron transfer mechanism in Co-P-B is a combination of the characteristics showcased by Co-B and Co-P catalysts individually. The optimized catalyst (Co-P-B-5) showed overpotentials of 145 mV and 290 mV to achieve the benchmark current density of 10 mA/cm2 for HER and OER, respectively, in 1 M NaOH. From theoretical calculations, it was observed that addition of P modulates the electron density at Co sites, thereby optimizing the H-adsorption capability, leading to higher HER rate. During anodic polarization, Co-P-B-5 shows formation of large number of CoOOH species on its surface, facilitating OER. Finally, stability, recyclability and wide-pH suitability of Co-P-B-5 was established to demonstrate its industrial viability.

Lamellar platinum–rhodium aerogels with superior electrocatalytic performance for both hydrogen oxidation and evolution reaction in alkaline environment

Hydrogen oxidation and evolution reactions (HOR and HER) in alkaline media are very kinetically sluggish, which becomes one of major barriers for the breakthrough of anion exchange membrane fuel cells. Thus, developing highly active and economically competitive HOR/HER electrocatalysts for alkaline electrolytes is of critical importance to realize future hydrogen economy. Herein, we for the first time report a new class of platinum-rhodium nanoalloy aerogel (PtRh NAA) via a facile and controllable strategy as exceptional HOR/HER electrocatalysts in alkaline environment. The as-synthesized PtRh NAA features unique lamellar architecture, hierarchical pores system and abundant low-coordinated sites. Benefiting from the combined structural and electronic effects as well as bifunctional synergetic effects, the lamellar PtRh NAA delivers an excellent HOR specific activity of 1.25 mA cm−2Pt+Rh, which is 5.5 times higher than that of the commercial Pt/C (0.225 mA cm−2Pt). Meanwhile, its HER overpotential at −10 mA cm−2 can be lowered to −55 mV, representing one of the highest HER activity so far. Moreover, no obvious deactivations are observed even after 5000 potential cycles for both HOR and HER, exhibiting excellent operation stability. These findings open a new field to design more advanced aerogels with high electrocatalytic performance.

Molecular and Material Engineering of Photocathodes Derivatized with Polyoxometalate-Supported {Mo3S4} HER Catalysts.

Molecular engineering of efficient HER catalysts is an attractive approach for controlling the spatial environment of specific building units selected for their intrinsic functionality required within the multistep HER process. As the {Mo3S4} core derived as various coordination complexes has been identified as one as the most promising MoSx-based HER electrocatalysts, we demonstrate that the covalent association between the {Mo3S4} core and the redox-active macrocyclic {P8W48} polyoxometalate (POM) produces a striking synergistic effect featured by high HER performance. Various experiments carried out in homogeneous conditions showed that this synergistic effect arises from the direct connection between the {Mo3S4} cluster and the toroidal {P8W48} units featured by a stoichiometry that can be tuned from two to four {Mo3S4} cores per {P8W48} unit. In addition, we report that this effect is preserved within heterogeneous photoelectrochemical devices where the {Mo3S4}-{P8W48} (thio-POM) assembly was used as cocatalyst (cocat) onto a microstructured p-type silicon. Using a drop-casting procedure to immobilize cocat onto the silicon interface led to high initial HER performance under simulated sunlight, achieving a photocurrent density of 10 mA cm-2 at +0.13 V vs RHE. Furthermore, electrostatic incorporation of the thio-POM anion cocat into a poly(3,4-ethylenedioxythiophene) (PEDOT) film is demonstrated to be efficient and straightforward to durably retain the cocat at the interface of a micropyramidal silicon (SimPy) photocathode. The thio-POM/PEDOT-modified photocathode is able to produce H2 under 1 Sun illumination at a rate of ca. 100 μmol cm-2 h-1 at 0 V vs RHE, highlighting the excellent performance of this photoelectrochemical system.

WXy /g-C3 N4 (WXy =W2 C, WS2 , or W2 N) Composites for Highly Efficient Photocatalytic Water Splitting.

The development of earth-abundant, economical, and efficient photocatalysts to boost water splitting is a key challenge for the practical large-scale application of hydrogen energy. In this study, g-C3 N4 loaded with different tungsten compounds (W2 C, WS2 , and W2 N) is found to exhibit enhanced photocatalytic activities. W2 C/g-C3 N4 displays the highest activity for the photocatalytic reaction with a H2 evolution rate of up to 98 μmol h-1 , as well as remarkable recycling stability. The excellent photocatalytic activity of W2 C/g-C4 N3 is attributed to the suitable band alignment in W2 C/g-C4 N3 and high HER activity of the W2 C cocatalyst, which promotes the separation and transfer of carriers and hydrogen evolution at the surface. These findings demonstrate that the tungsten carbide cocatalyst is more active for the photocatalytic reaction than the sulfide or nitride, paving a way for the design of novel and efficient carbides as cocatalysts for photocatalysis.

Highly Efficient Utilization of Precious Metals for Hydrogen Evolution Reaction with Photo‐Assisted Electro‐Deposited Urchin‐Like Te Nanostructure as a Template

AbstractIn this communication, the urchin‐like Te template is obtained by photo‐assisted electro‐deposition to replace trace platinum, gold and rhodium to obtain the Pt@Te‐PsS, Au@Te‐PsS and Rh@Te‐PsS catalysts in pursuit of their highly efficient utilization. The three‐dimensional structure of urchin‐like Te can not only accelerate the interface charge transfer, but also enhance the structural stability of the catalysts. Moreover, the electrons of Te are delocalized, to increase the electron density of interface and promote the hydrogen evolution reaction. Especially, the Pt@Te‐PsS catalyst with the Pt loading of only 1.08 wt % exhibits extremely outstanding electrocatalytic hydrogen evolution reaction activity. The finer hierarchical structure of Te template boosts the high HER performance with low precious metal loading, which highlights a new strategy for development of high‐efficiency electrocatalysts.

Facile and fast synthesis of Ni composite coating on Ti mesh by electrodeposition method for high-performance hydrogen production

Herein, the Ni composite coating comprised of metallic Ni (Ni0) and Ni(OH)2 was rapidly deposited on Ti mesh by facile, low cost and environmental-friendly electrodeposition method with only NiSO4 as electrolyte. HER experiments revealed that Ni composite coating on Ti mesh with electrodeposition time of 360 s (Ni/TM-360 s) exhibited the highest HER activity with overpotential of 205 mV at −10 mA/cm2, surpassing some previously reported Ni-based electrocatalysts. This catalyst also presented long-term durability. This method may provide an effective and green strategy for synthesizing Ni composite coating HER electrocatalyst with decent activity and stability.

In situ synthesis of a Fe3S4/MIL-53(Fe) hybrid catalyst for an efficient electrocatalytic hydrogen evolution reaction.

The development of efficient MOF-based electrocatalysts with good stability to produce hydrogen is a great challenge in the field of sustainable energy conversion. Herein, we introduced a controlled in-situ sulfurization strategy to generate a highly active and stable hybrid catalyst containing good conductive Fe3S4 ultrasmall nanosheets attached on the surface of 3D MIL-53(Fe) for the hydrogen evolution reaction in acidic solutions.

Ultra-small Mo2C nanodots encapsulated in nitrogen-doped porous carbon for pH-universal hydrogen evolution: insights into the synergistic enhancement of HER activity by nitrogen doping and structural defects

A facile one-pot synthesis method was used. The synergistic effect of nitrogen doping and structure defects on the carbon layer leaded to the high HER activity.

Novel nickel–cobalt phosphite with face-sharing octahedra derived electrocatalyst for efficient water splitting

Nickel–cobalt phosphite (CoNiPO) including local structural motifs with face-sharing octahedra shows excellent OER activity. The derivatized electrocatalyst (NiP2@CoNiPO) exhibits high HER activity. DFT calculations indicated the super-exchange effect in CoNiPO can adjust local electronic structure and improve their catalytic activity.

Abundant Vanadium Diboride with Graphene-like Boron layers for Hydrogen Evolution

We report on the design of abundant and highly active VB2 for hydrogen production. Density functional theory (DFT) calculations have predicted very high HER activity of the graphene-like B-layer, the V-terminated {100} layer, and the mixed V/B-terminated {101} layer of VB2. Bulk samples and nanoparticles of VB2 were synthesized and tested for their HER performance. The results indicate that both bulk and nano-VB2 are active for HER, consistent with theoretical predictions. In addition, the HER activity of VB2 is significantly increased at the nanoscale if compared to the bulk, reaching an overpotential of 192 mV at 10 mA/cm2 current density. Increased surface area and higher density of active sites are responsible for the higher nanoscale activity, making nano-VB2 the best HER boride to date in terms of abundance, stability, and activity in acidic solution.

Synthesis, characterization and applications of pH controlled Fe2O3 nanoparticles for electrocatalytic hydrogen evolution reaction

Non-noble and earth abundant catalysts provide an alternative route for efficient hydrogen evolution reaction of clean and renewable energy systems. Here, we report the synthesis of Fe2O3 nanoparticles by hydrothermal method by adjusting the pH value at 12 and 14 during the reaction. The as-synthesized samples are then subjected to structure and morphology characterization by x-ray diffraction and transmission electron microscopy. The chemical components of the as synthesized samples are characterized by x-ray photoelectron spectroscopy. Finally, the electrochemical measurements have been done to evaluate the catalytic performance of Fe2O3 nanoparticles. A high HER performance at pH 12 and pH 14 is well noticed for Fe2O3 nanoparticles by linear sweep voltammetry experiment, including a low overpotential of 321 mV and 423 mV at 10 mAcm−2 and Tafel slope values of 140 mv/dec and 144 mV/dec in basic medium, respectively. Moreover, the polarization curves after 1000 CV cycles has also shown the excellent stability of Fe2O3 nanoparticles for HER. Our work provides a new path for the design and synthesis of novel nanostructure electrocatalysts.

Mesoporous Mo2C/Carbon Hybrid Nanotubes Synthesized by a Dual-Template Self-Assembly Approach for an Efficient Hydrogen Production Electrocatalyst.

Molybdenum carbide-containing nanomaterials have drawn considerable attention in the application of hydrogen production electrocatalysts in light of the high abundance, low cost, and Pt-like electronic structure of molybdenum carbide. In this article, we report the synthesis of one-dimensional (1D) Mo2C/carbon mesoporous nanotubes (Mo2C/C PNTs) through a dual-template self-assembly approach, which employs 1D MoO3 nanobelts as the structure-directing template as well as one of the Mo2C precursors, along with block copolymer (BCP) micelles as the pore-forming template. In aqueous solution, the interface self-assembly of the micelles with pyrrole (Py) molecules absorbed in the PEO domains leads to the tight arrangement of the micelles on the surfaces of the MoO3 nanobelts. The polymerization of Py and the subsequent pyrolysis at 800 °C under a nitrogen atmosphere yield Mo2C/C PNTs with well-defined mesopores. Among the resultant Mo2C/C PNT samples, Mo2C/C PNTs with a specific surface area of 69 m2/g, a N atom percentage of 5.5 atom %, and an optimum Mo2C content of 40 wt % exhibit the highest HER catalytic performance in 0.5 M H2SO4 electrolyte, with a low onset potential of 34 mV, a satisfied overpotential of 140 mV at 10 mA/cm2, and excellent cycling stability. This study not only opens an avenue toward new Mo2C-containing nanomaterials but also provides a new system for the fundamental study on 1D porous nanohybrids with potential applications as hydrogen production electrocatalysts.