Optimizing Hydrogen Binding on Ru Sites with RuCo Alloy Nanosheets for Efficient Alkaline Hydrogen Evolution

Abstract

Ruthenium (Ru)‐based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru−H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru−H binding energy is the strong interaction between the 4normaldz2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4normaldz2 ‐band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy‐nanosheets (RuCo ANSs). They were prepared via a fast co‐precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z‐direction asymmetric coordination structure, obtaining an optimal 4normaldz2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru−H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra‐low overpotential of 10 mV at 10 mA cm−2 and a Tafel slope of 20.6 mV dec−1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal‐H binding energy of active sites.

Rapid preparation of carbon‐supported ruthenium nanoparticles by magnetic induction heating for efficient hydrogen evolution reaction in both acidic and alkaline media

“…Alloying is another strategy to control the electronic structure of Ru. For example, Cai et al 14 . synthesized ultrathin RuCo alloy nanosheets and observed a low overpotential (η 10 ) of −10 mV to reach the current density of 10 mA/cm 2 in 1 M KOH, consistent with results from DFT studies that Ni or Co could efficiently downshift the d‐band center of Ru and weaken H* adsorption.…”

“…Additionally, clearly defined lattice fringes can be resolved from these nanoparticles in high-resolution TEM measurements (Figure 2C), featuring two interplanar spacings of ca. 0.135 and 0.205 nm that can be ascribed to hcp Ru (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and (10)(11) facets (JCPDS-ICDD card No. 06-0663), respectively.…”

“…7 Ru atomically dispersed into g-C 3 N 4 or N-doped carbon also showed unprecedented HER performance in both alkaline and acidic media, owning to the unique Ru-N/C atomic coordination for optimal adsorption of H. [11][12][13] Alloying is another strategy to control the electronic structure of Ru. For example, Cai et al 14 synthesized ultrathin RuCo alloy nanosheets and observed a low overpotential (η 10 ) of −10 mV to reach the current density of 10 mA/cm 2 in 1 M KOH, consistent with results from DFT studies that Ni or Co could efficiently downshift the d-band center of Ru and weaken H* adsorption. Nonmetal elements have also been integrated into Ru producing RuX hybrids (X = B, Si, P, S, Se, and Te) to tune the electronic structure and the adsorption of H* on Ru.…”

Passivation of Cu nanosheet dissolution with Cu2+-containing electrolytes for selective electroreduction of CO2to CH4

“…Based on previous reports about the instability of Cu NSs caused by dissolution and theoretical analysis of the inhibition of Cu to Cu 2+ dissolution, [29][30][31] we made the following speculations about the influence of Cu 2+ content in solution on the stability of Cu NSs (Fig. 1).…”

Co-Based Nanosheets with Transitional Metal Doping for Oxygen Evolution Reaction

“…Co-based materials are widely used for OER due to their high intrinsic activity, processability at the atomic scale, and low-cost [ 24 , 25 ]. Albeit many strategies have been developed to generate Co-based materials, the common methods cannot generate amorphous nanosheets, such as the hydrothermal method, [ 26 ] sol–gel method [ 27 ], chemical vapor method [ 28 ], etc. In this work, we synthesized various Co-based amorphous nanosheets (ANSs) using the coprecipitation method in a cetyltrimethylammonium bromide (CTAB) solution.…”