Journal Article

# Atomic-Step Enriched Ruthenium–Iridium Nanocrystals Anchored Homogeneously on MOF-Derived Support for Efficient and Stable Oxygen Evolution in Acidic and Neutral Media

02 Mar 2021-ACS Catalysis (American Chemical Society (ACS))-Vol. 11, Iss: 6, pp 3402-3413
Abstract: Achieving an efficient and stable oxygen evolution reaction (OER) in an acidic or neutral medium is of paramount importance for hydrogen production via proton exchange membrane water electrolysis (...

Topics: Oxygen evolution (65%), Hydrogen production (56%), Ruthenium (55%) ... read more
##### Citations
More

8 results found

Journal Article
Siqi Niu1, Xiang-Peng Kong1, Siwei Li1, Yuanyuan Zhang1  +3 moreInstitutions (1)
Abstract: Oxygen evolution reaction (OER) in acidic media usually requires a catalyst with high content of noble Ir or Ru, becoming a bottleneck for the electrochemical water splitting. To address this issue, here we report the fabrication of a RuO2/(Co,Mn)3O4 nanocomposite with low Ru loading (2.51 wt%) as a highly efficient OER catalyst in acidic media (0.5 M H2SO4). Spectroscopic and theoretical studies demonstrate that the introduction of Mn in Co3O4 results in redistribution of electrons and the generation of electron-rich Ru species of the RuO2/(Co,Mn)3O4 catalyst. With modulated electronic properties, the adsorption of O on RuO2/(Co,Mn)3O4 is weakened and the rate determining step, formation of OOH*, of the OER process is therefore accelerated. At such a low Ru loading, RuO2/(Co,Mn)3O4 exhibits superior acidic OER activity (η =270 mV at 10 mA/cm2) and long‐term stability to the benchmark RuO2 catalyst. This work provides a new strategy for the design of cost-effective acidic OER electrocatalysts for energy conversion applications.

Topics: Catalysis (51%), Oxygen evolution (51%), Water splitting (50%)

7 Citations

Open accessJournal Article
Woo-Jae Lee1, Susanta Bera1, Hyun-Jae Woo1, Jung-Won An1  +3 moreInstitutions (2)
Abstract: Low-temperature fuel cells have attracted significant attention owing to their low cost and high performance. Herein, uniform Ru nanoparticles (NPs) with various size distributions were synthesized as a non-Pt catalyst on a carbon support by fluidized bed reactor-atomic layer deposition (FBR-ALD) as a function of ALD cycles for the hydrogen oxidation reaction (HOR) in alkaline medium. With an increase in the number of ALD cycles from 5 to 30 cycles, the wt% of the Ru NPs increased from ∼5 to ∼32 wt%. In addition, the structural characterization of the Ru NPs revealed the formation of Ru NPs with a uniform, dense, and controllable size (∼2–4 nm) and crystallinity depending on the growth cycle of ALD. However, the 10 cycled Ru catalyst with a NP size of ∼2 nm possessed a highly electrochemically active roughened surface (amorphous moiety covered the crystallite), which enhanced its HOR and mass activity. Remarkably, the ALD-synthesized Ru catalyst outperformed a commercial Ru/C catalyst with a similar wt%. Hydrogen binding energy (HBE) calculations revealed that the specific activity of the catalyst increased with decreasing HBE. The mechanistic pathway for the HOR indeed illustrates that enhanced activity under alkaline conditions was found owing to the weakening of the metal–H interaction influenced by the Ru NP crystallinity and size. The findings of this study indicate that the FBR-ALD technique is an effective, scalable approach for the synthesis of active non-Pt metal catalysts.

Topics: Catalysis (52%), , Crystallinity (51%)

2 Citations

Journal Article
Zhipeng Yu1, Junyuan Xu, Feng Siquan2, Feng Siquan3  +5 moreInstitutions (3)
Abstract: Rhodium (Rh) single-atom catalysts (SACs) supported on activated carbon (Rh1/AC) are prepared via a “top-down” chemical reaction-induced dispersion process using Rh nanoparticles as the starting materials. The as-obtained Rh1/AC exhibits hydrogen evolution activity and stability much better than those of the state-of-the-art Pt/C catalysts in alkaline solutions.

Topics: Rhodium (56%), Catalysis (55%)

1 Citations

Open accessJournal Article
Xiaojie Zhao1, Ying Chang1, Jiang Ji1, Jingchun Jia1  +1 moreInstitutions (1)
08 Oct 2021-RSC Advances
Abstract: Design and synthesis of electrocatalysts with high activity and low cost is an important challenge for water splitting. We report a rapid and facile synthetic route to obtain IrxNi clusters via polyol reduction. The IrxNi clusters show excellent activity for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic electrolytes. The optimized Ir2Ni/C clusters exhibit an electrochemical active area of 18.27 mF cm−2, with the overpotential of OER being 292 mV and HER being 30 mV at 10 mA cm−2, respectively. In addition, the Ir2Ni/C used as the cathode and anode for the H-type hydrolysis tank only needs 1.597 V cell voltages. The excellent electrocatalytic performance is mainly attributed to the synergistic effect between the metals and the ultra-fine particle size. This study provides a novel strategy that has a broad application for water splitting.

Topics: Water splitting (58%), Overpotential (55%), Oxygen evolution (53%)

Journal Article
Abstract: Green hydrogen produced by water electrolysis in combination with renewable energy is expected to become a key enabler for decarbonization of energy and transportation sectors as well as hard-to-abate industries, contributing to the achievement of carbon neutrality. Compared to the conventional alkaline water electrolysis technology, proton exchange membrane water electrolysis (PEMWE) possesses many advantages for green hydrogen production, but currently relies heavily on the expensive and scarce platinum group metals (PGMs) to catalyze the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which hinders widespread deployment of the PEMWE technology. This short review article briefly summarizes recent efforts dedicated to developing PGM-free HER and OER catalysts, with a focus on the emerging ones showing promising catalytic performance. Moreover, perspectives of future research on PGM-free catalysts are also outlined.

Topics: , Hydrogen production (55%),  ... read more

##### References
More

65 results found

Journal Article
Georg Kresse1, Jürgen Furthmüller2Institutions (2)
15 Oct 1996-Physical Review B
Abstract: We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices will be discussed. Our approach is stable, reliable, and minimizes the number of order ${\mathit{N}}_{\mathrm{atoms}}^{3}$ operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special metric'' and a special preconditioning'' optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calculations. It will be shown that the number of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order ${\mathit{N}}_{\mathrm{atoms}}^{2}$ scaling is found for systems containing up to 1000 electrons. If we take into account that the number of k points can be decreased linearly with the system size, the overall scaling can approach ${\mathit{N}}_{\mathrm{atoms}}$. We have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable. \textcopyright{} 1996 The American Physical Society.

Topics: DIIS (51%)

64,484 Citations

Open accessJournal Article
Peter E. Blöchl1Institutions (1)
15 Dec 1994-Physical Review B
Abstract: An approach for electronic structure calculations is described that generalizes both the pseudopotential method and the linear augmented-plane-wave (LAPW) method in a natural way. The method allows high-quality first-principles molecular-dynamics calculations to be performed using the original fictitious Lagrangian approach of Car and Parrinello. Like the LAPW method it can be used to treat first-row and transition-metal elements with affordable effort and provides access to the full wave function. The augmentation procedure is generalized in that partial-wave expansions are not determined by the value and the derivative of the envelope function at some muffin-tin radius, but rather by the overlap with localized projector functions. The pseudopotential approach based on generalized separable pseudopotentials can be regained by a simple approximation.

Topics: , Pseudopotential (58%)

48,474 Citations

Journal Article
Georg Kresse1, Daniel P. Joubert2Institutions (2)
15 Jan 1999-Physical Review B
Abstract: The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Bl\"ochl's projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addition, critical tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed core all electron methods. These tests include small molecules $({\mathrm{H}}_{2}{,\mathrm{}\mathrm{H}}_{2}{\mathrm{O},\mathrm{}\mathrm{Li}}_{2}{,\mathrm{}\mathrm{N}}_{2}{,\mathrm{}\mathrm{F}}_{2}{,\mathrm{}\mathrm{BF}}_{3}{,\mathrm{}\mathrm{SiF}}_{4})$ and several bulk systems (diamond, Si, V, Li, Ca, ${\mathrm{CaF}}_{2},$ Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.

Topics: Cauchy stress tensor (53%)

46,297 Citations

Journal Article
Georg Kresse1, Jürgen Furthmüller2Institutions (2)
Abstract: We present a detailed description and comparison of algorithms for performing ab-initio quantum-mechanical calculations using pseudopotentials and a plane-wave basis set. We will discuss: (a) partial occupancies within the framework of the linear tetrahedron method and the finite temperature density-functional theory, (b) iterative methods for the diagonalization of the Kohn-Sham Hamiltonian and a discussion of an efficient iterative method based on the ideas of Pulay's residual minimization, which is close to an order Natoms2 scaling even for relatively large systems, (c) efficient Broyden-like and Pulay-like mixing methods for the charge density including a new special ‘preconditioning’ optimized for a plane-wave basis set, (d) conjugate gradient methods for minimizing the electronic free energy with respect to all degrees of freedom simultaneously. We have implemented these algorithms within a powerful package called VAMP (Vienna ab-initio molecular-dynamics package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semi-conducting surfaces, phonons in simple metals, transition metals and semiconductors) and turned out to be very reliable.

Topics: , , Iterative method (54%) ... read more

40,008 Citations

Journal Article
Georg Kresse1, Jürgen Hafner1Institutions (1)
01 Jan 1993-Physical Review B
Abstract: We present ab initio quantum-mechanical molecular-dynamics calculations based on the calculation of the electronic ground state and of the Hellmann-Feynman forces in the local-density approximation at each molecular-dynamics step. This is possible using conjugate-gradient techniques for energy minimization, and predicting the wave functions for new ionic positions using subspace alignment. This approach avoids the instabilities inherent in quantum-mechanical molecular-dynamics calculations for metals based on the use of a fictitious Newtonian dynamics for the electronic degrees of freedom. This method gives perfect control of the adiabaticity and allows us to perform simulations over several picoseconds.