HER Catalysts Research Articles

Fe-doped Co9S8 nanosheets on carbon fiber cloth as pH-universal freestanding electrocatalysts for efficient hydrogen evolution

Heteroatom doping is a feasible approach to adjust catalytic performance of the HER catalysts. In this work, we report a design of Fe-doped Co9S8 nanosheets grown on carbon cloth (Fe-Co9S8 NSs/CC) as a hydrophilic 3D monolithic electrocatalyst for efficient hydrogen evolution under all pH. The water contact angle and electrochemical measurements proved that the resultant material was hydrophilic for its nano hierarchitectures and dopant Fe enhanced the catalytic capability of singular Co9S8. In 1.0 M KOH, the Fe-Co9S8 NSs/CC possessed a relatively small Tafel slope (95.3 mV dec−1) and required the overpotential of 83 mV to achieve 10 mA cm−2. To drive the same current density, the overpotentials were 65 and 192 mV in 0.5 M H2SO4 and 1.0 M PBS, respectively. Meanwhile, it showed good cycle stability and durability over 20 h static test at alkaline and neutral condition. The flexible freestanding catalyst has great potential in practical applications.

Functionalized Carbon Nanotubes for Highly Active and Metal-Free Electrocatalysts in Hydrogen Evolution Reaction

Six kinds of functionalized multiwalled carbon nanotubes (FCNTs) with different functional moieties were utilized as metal-free electrocatalysts towards the hydrogen evolution reaction for the first time. Ethylenediamine-functionalized multiwalled carbon nanotubes (EDA-CNTs) delivered the best HER activity holding a low-onset overpotential of 150 mV, a Tafel slope of 116 mV dec−1, and a Faradaic efficiency (FE) of 94% with a good stability. This HER activity of EDA-CNTs is superior or quite comparable to other reported metal-free HER catalysts, while the preparation of this electrocatalyst is simple, quick, and inexpensive. This good HER performance of EDA-CNTs can be resulted from the high electrical conductivity and its high grafting yield to form more amide groups for enhancement of proton adsorption. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were successfully used to elucidate the HER process promoted by EDA-CNTs, in which the amide groups were demonstrated to improve the proton adsorption.

Vertically aligned MoS2 on Ti3C2 (MXene) as an improved HER catalyst

Vertically aligned interlayer expanded (IE) MoS2 on a Ti3C2Tx (MXene) support as an efficient electrocatalytic HER catalyst.

Microwave-assisted preparation of Ag/Ag2S carbon hybrid structures from pig bristles as efficient HER catalysts

A microwave-assisted method for the production of HER catalyst Ag/Ag2S carbon hybrids through the valorisation of pig bristles is described.

Copper–nickel embedded into a nitrogen-doped carbon octahedron as an effective bifunctional electrocatalyst

The CuNi-NC serves as an efficient bifunctional catalyst for HER and OER, in which the role of Ni is investigated in detail.

Plasmon-enhanced electrocatalytic hydrogen/oxygen evolution by Pt/Fe–Au nanorods

Plasmonic dumbbell-like gold nanorods were selected as models to further investigate the SPR effect on electrocatalysis. Under the excitation of localized surface plasmon resonance of Pt/Fe–Au gold nanorods, the electrocatalytic activity of this catalyst for HER and OER was well improved.

Hierarchical whisker-on-sheet NiCoP with adjustable surface structure for efficient hydrogen evolution reaction.

We have reported the synthesis of hierarchical whisker-on-sheet (HWS) NiCoP anchored on Ni foam with adjustable surface structure for efficient hydrogen evolution reaction (HER). The HWS NiCoP was obtained by controllable phosphidation of HWS Ni-Co-carbonates hydroxide precursor grown on Ni foam (NF). The experimental parameters were optimally tuned to understand the formation process of the precursor and to regulate the microstructure of the materials. The test results indicated that the HWS NiCoP/NF can produce a current density of 10 mA cm-2 (η10) at a low overpotential of 59 mV and a current density of 100 mA cm-2 (η100) at an overpotential of 220 mV for HER. Notably, upon surface activation with KOH, the HER performance of HWS NiCoP/NF could be dramatically enhanced with η10 and η100 values of 42 mV and 141 mV, respectively. The HWS NiCoP/NF showed a superior performance to NiCoP displaying other morphologies (sheets and wires etc.) The good performance of HWS NiCoP/NF should be attributed to their special whisker-on-sheet structures that are favourable for effective contact with the electrolyte. Also, hydrated metals can be formed on surface after the alkali treatment step, which is beneficial to moderate the bonding to hydrogen and thus, improve the HER activity. The present study will be indicative toward the construction of highly-efficient HER catalysts by regulating the structure of the materials.

Cost-effective and environmentally friendly synthesis of 3D Ni2P from scrap nickel for highly efficient hydrogen evolution in both acidic and alkaline media

A strategy combining photochemical vapor generation with low temperature deposition and phosphorization was developed to synthesize a 3D Ni2P HER catalyst.

3D nanoporous Ni/V2O3 hybrid nanoplate assemblies for highly efficient electrochemical hydrogen evolution

A 3D nanoporous Ni/V2O3 nanoplate assembly is developed as an efficient HER catalyst via a self-templated strategy.

A highly efficient Ni–Mo bimetallic hydrogen evolution catalyst derived from a molybdate incorporated Ni-MOF

A bimetallic Ni–Mo nanocomposite as a highly efficient HER catalyst with critical synergetic effect can be obtained from a molybdate incorporated Ni-MOF.

Raymond Schaak

Angewandte Chemie International EditionVolume 57, Issue 12 p. 3002-3002 Author ProfileFree Access Raymond Schaak First published: 24 November 2017 https://doi.org/10.1002/anie.201711024Citations: 2AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “The downside of my job is having to sometimes be the bearer of bad news. My favorite food is anything I can cook on a grill, especially salmon ...” This and more about Raymond Schaak can be found on page 3002. Raymond Schaak The author presented on this page has published more than 10 articles in Angewandte Chemie in the last 10 years, most recently: “Size and Interface Modulated Metal–Insulator Transition in Solution-Synthesized Nanoscale VO2–TiO2–VO2 Heterostructures”: Angew. Chem. Int. Ed. 2017, 56, 15348; Angew. Chem. 2017, 129, 15550. The work of R. E. Schaak has been featured on the cover of Angewandte Chemie: “Sequential Anion and Cation Exchange Reactions for Complete Material Transformations of Nanoparticles with Morphological Retention”: J. M. Hodges, K. Kletetschka, J. L. Fenton, C. G. Read, R. E. Schaak, Angew. Chem. Int. Ed. 2015, 54, 8669; Angew. Chem. 2015, 127, 8793. Date of birth: October 12, 1975 Position: DuPont Professor of Materials Chemistry, Penn State University E-mail: res20@psu.edu Homepage: http://chem.psu.edu/directory/res20 ORCID: 0000-0002-7468-8181 Education: 1998 BS, Lebanon Valley College, Pennsylvania 2001 PhD supervised by Thomas Mallouk, Penn State University 2001–2003 Postdoc with Robert Cava, Princeton University Awards: 2006 Beckman Young Investigator Award; 2006 DuPont Young Professor; 2007 Sloan Research Fellow; 2007 Camille Dreyfus Teacher–Scholar Award; 2011 National Fresenius Award; 2016 Inorganic Nanoscience Award, ACS Current research interests: Synthetic inorganic nanochemistry; retrosynthetic design of solid-state materials; nanoparticle synthesis; chemical reactions of nanoparticles; nanoparticle formation pathways; new materials discovery; earth-abundant catalytic materials for energy applications Hobbies: Photography, painting, music, road trips The downside of my job is having to sometimes be the bearer of bad news. My favorite food is anything I can cook on a grill, especially salmon. My favorite quote is “fortune favors the prepared mind” (Pasteur). The biggest problem that scientists face is communicating the excitement, importance, and implications of fundamental research to many different audiences. What I look for first in a publication is the key result(s)—what is new in it that advances the field. The most important thing I learned from my parents is the value of balance and priorities in life: work hard, but also make time for family, friends, hobbies, and rest. My favorite place on earth is a place (not to be named!) where I can escape without access to internet or a phone for a few days. I chose chemistry as a career because I liked doing experiments, using math to solve problems, and piecing together different concepts in creative ways. In high school, chemistry “clicked” as a career where I could integrate these interests. My not-so-secret passion is macro photography. I like taking pictures of the small things in the world around us that we wouldn't normally see. If I were not a scientist, I would be a graphic designer, a photographer, or an architect. I lose track of time when I am doing something creative, like photography, art, or brainstorming. My 5 top papers: 1“Metallurgy in a Beaker: Nanoparticle Toolkit for the Rapid Low-Temperature Solution Synthesis of Functional Multimetallic Solid State Materials”: R. E. Schaak et al., J. Am. Chem. Soc. 2005, 127, 3506. (Defined our approach to using nanoparticles as reagents for low-temperature solid-state reactions.) 2“Orthogonal Reactivity of Metal and Multimetal Nanostructures for Selective, Stepwise, and Spatially-Controlled Solid State Modification”: B. M. Leonard, M. E. Anderson, K. D. Oyler, T. H. Phan, R. E. Schaak, ACS Nano 2009, 3, 940. (Our vision for applying molecule-inspired orthogonal reactivity to nanoparticles.) 3“A total-synthesis framework for the construction of high-order colloidal hybrid nanoparticles”: M. R. Buck, J. F. Bondi, R. E. Schaak, Nature Chem. 2012, 4, 37. (Applies concepts from natural-product synthesis to complex multicomponent nanoparticles.) 4“Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction”: E. J. Popczun, J. R. McKone, C. G. Read, A. J. Biacchi, A. M. Wiltrout, N. S. Lewis, R. E. Schaak, J. Am. Chem. Soc. 2013, 135, 9267. (Transition-metal phosphides were introduced as a viable family of earth-abundant HER catalysts.) 5“Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals”: J. L. Fenton, R. E. Schaak, Angew. Chem. Int. Ed. 2017, 56, 6464; Angew. Chem. 2017, 129, 6564. (Multiple distinct crystal structures can be retained during nanocrystal cation exchange.) Citing Literature Volume57, Issue12March 12, 2018Pages 3002-3002 ReferencesRelatedInformation

Transition-Metal Phosphide-Carbon Nanosheet Composites Derived from Two-Dimensional Metal-Organic Frameworks for Highly Efficient Electrocatalytic Water-Splitting.

The preparation of highly active, sustainable, nonprecious metal materials as hydrogen evolution and oxygen evolution reaction (HER and OER) catalysts that can relieve the environmental pollution and energy shortage problems present a great challenge to chemists. We herein report the fabrication of a highly active metal phosphide-carbon composite catalyst for HER and OER in acid and basic solution, respectively. The catalyst is derived through carbonization and subsequent phosphorization of two-dimensional (2D) cobalt porphyrinic metal-organic framework nanosheets. It consists of cobalt phosphide nanoparticles embedded in mesoporous N-doped graphitic carbon materials. The catalyst shows good electrocatalytic activities for HER in 0.5 M H2SO4 and OER in 1 M KOH with overpotentials of 98 and 370 mV at a current density of 10 mA cm-2 and the Tafel slopes of 74 and 79 mV dec-1, respectively. In addition, the catalyst also shows good durability. The method used in this study could be applied to prepare new, highly efficient water-splitting catalysts by using diverse 2D metal-organic frameworks as templates.

A novel structure of Ni-(MoS2/GO) composite coatings deposited on Ni foam under supergravity field as efficient hydrogen evolution reaction catalysts in alkaline solution

We report a novel and simple approach to synthesis highly efficient and stable electrochemical catalyst of Ni-(MoS2/GO) composite coatings by electrodeposition from aqueous solution with the nickel sulphamate precursor. Depositing under supergravity fields has been applied to scatter more MoS2/GO hybrids in the coatings and decrease the size of nickel particles as far as possible and increase large amount of exposed active sites. In 1.0M NaOH solution, Ni-(MoS2/GO) only needs overpotentials as low as −33mV and −132mV at a current density of −10mAcm−2 and −100mAcm−2, respectively. The behavior of Ni-(MoS2/GO) exceeds most of the same reported HER catalysts in previously literature. In addition, we also synthesized Ni-MoS2, Ni-GO and pure Ni catalysts use the same method. The results show that Ni-(MoS2/GO) exhibited better HER activity at a current density of −100mAcm−2 than these catalysts. In the future research field of HER catalysis materials, the development of this material may be not limited to nickel based materials, also will be used in Fe, Co and other non noble metal based materials, outlining a general approach for the synthesis of nanostructured M-(MoS2/GO) as a class of new catalyst with efficient HER activity.

In-situ potentiostatic activation to optimize electrodeposited cobalt-phosphide electrocatalyst for highly efficient hydrogen evolution in alkaline media

We first report a novel cobalt-phosphide (Co-P) hybrid with flake-like structure by a facile one-step electrodeposition combined with in-situ potentiostatic activation technique. Exotic microstructure transformation of Co-P hybrid from microspheres to nanosheets has been noted during the activation process. The Co-P catalyst exhibits striking kinetic metrics with an overpotential of 85mV (at 10mAcm–2) and Tafel slope of 37mVdec–1, performing among the best of all the HER catalysts in strong alkaline media (at pH 14). This study offers a new in-situ approach to optimize catalytic materials for high-performance electrocatalysts towards energy-related applications.

The hydrogen evolution reaction on gold nanoparticles modified MoS<sub>2</sub> nanosheets

Hydrogen has been considered as the clean and renewable energy source of the next generation by virtue of its high energy density and environmentally friendly combustion product. Electrochemically evolving hydrogen by splitting water is one of the most efficient strategies for hydrogen generation. Previous studies have revealed that two-dimensional layered molybdenum disulfide (MoS 2 ) based materials would be the promising HER catalysts. Tuning the electronic density of MoS 2 electrocatalyst has emerged as an effective strategy to optimize the electrocatalytic activities. Herein, we utilized in-situ reduction method to synthesize gold nanoparticles modified MoS 2 nanosheets (Au-MoS 2 ) hybrid. X-ray photoelectron spectroscopy and Raman spectroscopy were used to confirm the strong electronic interaction between Au and MoS 2 . The Au-MoS 2 shows superior electrocatalytic activity towards HER, as evidenced by the onset potential decreased by 50 mV as compared to ce-MoS 2 . The HER enhancement can be largely attributed to the increase of carrier density in MoS 2 injected from Au nanoparticles, which results in the modulation of the energy level of MoS 2 more comparable to HER.

(Invited) Carbide/Nitride and Bimetallic Catalysts for Water Electrolysis

The high cost and impurity tolerance of Pt-group metal electrocatalysts used for HER and OER are significant challenges to overcome in order to achieve wide-spread electrolyzer use. Discovery of active, inexpensive, and impurity tolerant electrocatalysts should be guided by activity trends derived from density functional theory (DFT) calculations and experimental studies on well-characterized thin films. These trends then need to be extended to industrially relevant high surface area catalysts in order to bridge the materials gap. In this talk we will use three examples to illustrate our efforts in reducing or replacing Pt-group metals for HER and OER. The first example is the utilization of monolayer (ML) Pt-group metals over transition metal carbide (TMC) substrates for HER in acid electrolyte. Metal-modified TMCs are promising inexpensive replacements for Pt-group metals because they have shown the ability to tune hydrogen binding energy, which is a descriptor for predicting the HER activity in acid. We will also use ML Pt-NbC thin films to compare the HER activity in acid and alkaline electrolytes, and to illustrate the impurity tolerance of Pt-NbC in the presence of tap water ions. The second example utilizes non-precious bimetallic catalysts for HER in alkaline electrolyte. The value of hydrogen binding energy appears to be a useful descriptor for predicting monometallic and bimetallic catalysts for HER in alkaline electrolyte. The last example shows the feasibility of coating monolayer coverages of IrO2 on transition metal nitrides for OER in acid electrolyte. All three examples demonstrate the importance of correlating theoretical calculations with experimental measurements for identifying alternative electrocatalysts for water electrolysis.

Interfacial Effect Study of Alkaline Membrane Media Using Microelectrodes

Interfacial issues at anion exchange membranes greatly influence the electrocatalysis at high pH environment especially in conjunction with an anion exchange membrane. In this context it is well known that carbonate ions in the context of a prototypical anion exchange membrane such as A 201 (Tokuyama, Japan) are strongly adsorbing anions and thus can suppress HOR kinetics. Not only can carbonate ions block catalyst active sites, but they can also lower the amount of hydroxyl ions for adsorption at low pH. Moreover, corresponding ionomers such as AS-4 (Tokuyama, Japan) has a negative effect on HOR activity in the context of Pt, as shown in Figure 1c. At NUCRET, we successfully concluded the effect of carbonates in conjunction of anion exchange membrane as well as the role of corresponding ionomers such as AS-4. In this study we further extend this investigation by including microelectrodes in two different media - carbonate and hydroxide - for HER (Pt microelectrode) and OER (Ir microelectrode). Hence this presentation will include the following work: Using A 201 in hydroxide form and carbonate form in the Solid State Cell setup (Figure 1a), under the following scenarios: 1) Water fed vs. KOH vs.K2CO3 continuous feed (for electrolytes, equal conductivity and equal pH conditions); 2) HER/HOR and OER/ORR while feeding electrolyte from the top, bottom, or both. This study is aimed at understanding the improvements observed when feeding a low concentration of carbonate at the anode interface (OER electrode) during water electropysis (Figure 1b). We hypothesize that the improvement could be because of the conductivity boost from 1% carbonate, because of different reaction mechanisms between HER (cathode side) and OER, or both. This micro-electrode study therefore is designed to not only mimic carbonate vs. hydroxide at the membrane interface via directional feed of carbonate ions (i.e., top where the microelectrode is at an interface with the membrane) or bottom to mimic mass transport and kinetics at the membrane interface. Transferring this study to the practical water splitting cell, will provide a thorough insight of the reactions between the catalyst layer and the membrane while feeding water vs. different electrolytes. It is particularly important to note that A-201 standard (Tokuyama, Japan) represents the state-of-the-art in alkaline membranes. Currently, our partner - Proton On-Site provides the full cell scale-up water splitting stack with the use of our best non-PGM catalysts for HER (60% Ni-Cr/C) and OER (40% Ni-Fe/Raney-PANI), as well as feeding 1% carbonate on the anode side. Figure 1

(Invited) Developing Efficient Electrocatalysts for the Hydrogen and Oxygen Evolution Reactions

Water electrolysis is one of the crucial means for converting electricity generated from solar and wind based power sources into clean H2 fuels. The efficiency of this process depends largely on the catalytic property of the cathode and anode.We present here our work to develop and understand electrocatalysts used for the oxygen (OER) and hydrogen (HER) evolution reactions. Using operando Raman spectroscopy, we shall first show how the structure of amorphous MoS x (an excellent HER catalyst) evolves during H2 evolution. Furthermore, we have identified the S atoms therein as the catalytically active sites responsible for proton reduction. Density functional theory calculations were performed on a variety of MoS x structures and corroborated the assignments of the observed vibrational frequencies. We shall also present our Raman and X-ray absorption spectroscopy study of Cu oxides during O2 evolution. This investigation has allowed us to propose CuIIIoxides as highly active catalytic species for the electrochemical water oxidation. Mixed metal composites based on Mo and W have also been shown to exhibit excellent HER activities. We elucidated the catalytic roles of the different elements therein such as nitrogen, carbon, molybdenum, etc , and proposed plausible mechanisms of their workings. We shall show that some of these catalysts are robust against deactivation even in contaminated electrolytes. Finally, we present an overview of our recent work to couple photovoltaics to an electrocatalytic cell for the efficient reduction of carbon dioxide. 1. Y.L. Deng, L.R.L. Ting, P.H.L. Neo, Y.J. Zhang, A.A. Peterson, and B.S. Yeo. ACS Catal. 6, 7790. 2016. 2. Y.L. Deng, A.D. Handoko, Y.H. Du, S.B. Xi and B.S. Yeo. ACS Catal. 6, 2473. 2016 3. L.R.L. Ting, Y.L. Deng, L. Ma, Y.J. Zhang, A.A. Peterson, and B.S. Yeo. ACS Catal. 6, 861. 2016 4. U. Joshi, J. Lee, C. Giordano, S. Malkhandi and B.S. Yeo. Phys. Chem. Chem. Phys. 18, 21548. 2016.

One-pot synthesis of nickel sulfide with sulfur powder as sulfur source in solution and their electrochemical properties for hydrogen evolution reaction

Among low-cost and earth-abundant elements, the nickel-based HER catalysts, particularly nickel sulfide, are considered as one of the most promising candidates in this field. In this paper, a kind of spherical nickel sulfide material was obtained using nickel acetate and sulfur powder as precursors by one-pot synthesis. The use of sulfur powder as sulfur source with solution-based method will enable the synthesis of metal sulfides to be more simple and capable of mass production. In addition, the as-synthesized nickel sulfide exhibits an onset overpotential of as low as 25mV, a Tafel slope of 90mVdec−1, and an exchange current density of 0.44mAcm−2. Furthermore, this catalyst maintains its catalytic activity for at least 25h and only requires overpotentials of 42 and 113mV to attain current densities of 2 and 10mAcm−2, respectively. The electrocatalytic performance is promising for applications as non-noble-metal HER catalyst with water splitting for hydrogen production.

Boosting Hydrogen Evolution Activities by Strong Interfacial Electronic Interaction in ZnO@Bi(NO3)3 Core–Shell Structures

Base-free hydrogen evolution from formaldehyde solution represents one of the most important reactions in the fuel cell based hydrogen economy. However, limited progresses have been made in the rational design of cheap and efficient heterogeneous catalysts for this reaction. Here, we for the first time propose a Lewis acid–base combination strategy to design efficient heterogeneous catalysts for HER from HCHO/H2O. By utilizing the Lewis acid/base properties of Bi(NO3)3·5H2O/ZnO, we successfully fabricated core–shell structured ZnO@Bi(NO3)3 composites. A strong interfacial electronic interaction between ZnO and Bi(NO3)3·5H2O is evidenced by the unprecedented 3.3 eV upshift of Zn 2p and 0.5 eV downshift of Bi 4f, which boosts the HER activities of inert ZnO and Bi(NO3)3·5H2O. Destroying the interfacial electronic interaction leads to a fast deactivation while increasing interfacial sites proportionally enhances the activity, indicating that interfacial sites are real active sites. DFT calculations confirm t...