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Single-atom catalysts (SACs) exhibit intriguing catalytic performance owing to their maximized atom utilizations and unique electronic structures. However, the reported strategies for synthesizing SACs generally have special requirements for either the anchored metals or the supports. Herein, we report a universal approach of electrochemical deposition that is applicable to a wide range of metals and supports for the fabrication of SACs. The depositions were conducted on both cathode and anode, where the different redox reactions endowed the SACs with distinct electronic states. The SACs from cathodic deposition exhibited high activities towards hydrogen evolution reaction, while those from anodic deposition were highly active towards oxygen evolution reaction. When cathodically- and anodically-deposited Ir single atoms on Co 0.8 Fe 0.2 Se 2 @Ni foam were integrated into a two-electrode cell for overall water splitting, a voltage of 1.39 V was required at 10 mA cm −2 in alkaline electrolyte. While single-atom catalysts exhibit intriguing catalytic performances and electronic structures, syntheses are often tailored to a particular system. Here, authors report electrochemical deposition as a universal approach for the fabrication of single-atom catalysts over range of metals and supports.

It is known that the main-group metals and their related materials show poor catalytic activity due to a broadened single resonance derived from the interaction of valence orbitals of adsorbates with the broad sp-band of main-group metals. However, Mg cofactors existing in enzymes are extremely active in biochemical reactions. Our density function theory calculations reveal that the catalytic activity of the main-group metals (Mg, Al and Ca) in oxygen reduction reaction is severely hampered by the tight-bonding of active centers with hydroxyl group intermediate, while the Mg atom coordinated to two nitrogen atoms has the near-optimal adsorption strength with intermediate oxygen species by the rise of p-band center position compared to other coordination environments. We experimentally demonstrate that the atomically dispersed Mg cofactors incorporated within graphene framework exhibits a strikingly high half-wave potential of 910 mV in alkaline media, turning a s/p-band metal into a highly active electrocatalyst. Although magnesium-based cofactors are highly active in biochemical reactions, magnesium-based materials generally exhibit poor catalytic activity for oxygen reduction. Here the authors enhance electrocatalytic activity of magnesium through atomic dispersion with a graphene framework.

The homogeneity of single-atom catalysts is only to the first-order approximation when all isolated metal centers interact identically with the support. Since the realistic support with various topologies or defects offers diverse coordination environments, realizing real homogeneity requires precise control over the anchoring sites. In this work, we selectively anchor Ir single atoms onto the three-fold hollow sites (Ir 1 /T O –CoOOH) and oxygen vacancies (Ir 1 /V O –CoOOH) on defective CoOOH surface to investigate how the anchoring sites modulate catalytic performance. The oxygen evolution activities of Ir 1 /T O –CoOOH and Ir 1 /V O –CoOOH are improved relative to CoOOH through different mechanisms. For Ir 1 /T O –CoOOH, the strong electronic interaction between single-atom Ir and the support modifies the electronic structure of the active center for stronger electronic affinity to intermediates. For Ir 1 /V O –CoOOH, a hydrogen bonding is formed between the coordinated oxygen of single-atom Ir center and the oxygenated intermediates, which stabilizes the intermediates and lowers the energy barrier of the rate-determining step. While single-atom catalysts offer well-defined structures, the homogeneity of the active sites is determined by localized coordination environments. Here, authors anchor Ir single atoms onto different sites on CoOOH and show how their distinct coordinations activate oxygen-evolving electrocatalysis

This study investigates the nature of the X 0 ( 2900 ) and χ c 0 ( 3930 ) based on experimental results of the process B + → D + D - K + . We focus on the S-wave D ∗ - K ∗ + and D s + D s - molecular states, which can be related to the X 0 ( 2900 ) and χ c 0 ( 3930 ) , respectively. Using effective Lagrangians, we construct the potential kernel of the D ∗ - K ∗ + – D - K + and D s + D s - – D + D - interactions with a one-boson-exchange model, and determine the scattering amplitudes and their poles through a quasipotential Bethe–Salpeter equation approach. By incorporating the potential kernel into the three-body decay process B + → D + D - K + , we evaluate the D - K + and D + D - invariant mass spectra, as well as the Dalitz plot, using Monte Carlo simulation. A satisfactory fit to the D - K + and D + D - invariant mass spectra is achieved after introducing additional Breit–Wigner resonances, X 1 ( 2900 ) , ψ ( 3770 ) , and χ c 2 ( 3930 ) . Prominent signals of the X 0 ( 2900 ) and χ c 0 ( 3930 ) states appear as peaks in the D - K + and D + D - invariant mass spectra near 2900 and 3930 MeV, respectively. Clear event concentration from the X 0 ( 2900 ) and χ 0 ( 3930 ) is evident as strips in the Dalitz plot. The results suggest that both X 0 ( 2900 ) and χ c 0 ( 3930 ) can be interpreted as molecular states, with the inclusion of X 1 ( 2900 ) and χ 2 ( 3930 ) necessary to describe structures in the D - K + and D + D - invariant mass spectra, respectively.

This study investigates the three-body decay process B + → D ∗ + D - K + , aiming to explore the possible origins of T c ¯ s ¯ 0 ∗ ( 2870 ) 0 and χ c 1 ( 3872 ) as intermediate states. Within the molecular state framework, T c ¯ s ¯ 0 ∗ ( 2870 ) 0 and χ c 1 ( 3872 ) are considered as possible D ¯ ∗ K ∗ and D ∗ D ¯ molecular states, respectively. Using effective Lagrangians, the interaction kernels of the D ¯ ∗ K ∗ and D ∗ D ¯ systems are constructed within the one-boson-exchange model. The corresponding rescattering amplitudes and pole positions are obtained by solving the quasipotential Bethe–Salpeter equation. These amplitudes are incorporated into the decay amplitude of the three-body process, and the D - K + and D ∗ + D - invariant mass spectra are simulated via Monte Carlo methods. To better reproduce the experimental data, additional Breit–Wigner contributions from T c ¯ s ¯ 1 ∗ ( 2900 ) 0 , χ c 1 ( 4010 ) , and h c ( 4300 ) are included. The results show a pronounced enhancement near 2900 MeV in the D - K + invariant mass spectrum, strongly supporting the interpretation of T c ¯ s ¯ 0 ∗ ( 2870 ) 0 as a D ¯ ∗ K ∗ molecular state. While the D ¯ ∗ K ∗ molecular state provides a reasonable contribution to the D - K + spectrum, the D ∗ D ¯ molecular state yields no significant effect on either the D - K + or D ∗ + D - distributions. This suggests that the observed χ c 1 ( 3872 ) structure around 3872 MeV may not be interpreted as a D ∗ D ¯ molecular state.

In this work, we perform a systematical investigation about the possible hidden and doubly heavy molecular states with open and hidden strangeness from interactions of D(∗)D¯s(∗)/B(∗)B¯s(∗), Ds(∗)D¯s(∗)/Bs(∗)B¯s(∗), D(∗)Ds(∗)/B(∗)Bs(∗), and Ds(∗)Ds(∗)/Bs(∗)Bs(∗) in a quasipotential Bethe-Salpeter equation approach. The interactions of the systems considered are described within the one-boson-exchange model, which includes exchanges of light mesons and J/ψ/Υ meson. Possible molecular states are searched for as poles of scattering amplitudes of the interactions considered. The results suggest that recently observed Zcs(3985) can be assigned as a molecular state of D∗D¯s+DD¯s∗, which is a partner of Zc(3900) state as a DD¯∗ molecular state. The calculation also favors the existence of hidden heavy states DsD¯s/BsB¯s with spin parity JP=0+, DsD¯s∗/BsB¯s∗ with 1+, and Ds∗D¯s∗/Bs∗B¯s∗ with 0+, 1+, and 2+. In the doubly heavy sector, the bound states can be found from the interactions (D∗Ds+DDs∗)/(B∗Bs+BBs∗) with 1+, DsD¯s∗/BsB¯s∗ with 1+, D∗Ds∗/B∗Bs∗ with 1+ and 2+, and Ds∗Ds∗/Bs∗Bs∗ with 1+ and 2+. Some other interactions are also found attractive, but may be not strong enough to produce a bound state. The results in this work are helpful for understanding the Zcs(3985), and future experimental search for the new molecular states.

Supported ordered intermetallic compounds exhibit superior catalytic performance over their disordered alloy counterparts in diverse reactions. But the synthesis of intermetallic compounds catalysts often requires high-temperature annealing that leads to the sintering of metals into larger crystallites. Herein, we report a small molecule-assisted impregnation approach to realize the general synthesis of a family of intermetallic catalysts, consisting of 18 binary platinum intermetallic compounds supported on carbon blacks. The molecular additives containing heteroatoms (that is, O, N, or S) can be coordinated with platinum in impregnation and thermally converted into heteroatom-doped graphene layers in high-temperature annealing, which significantly suppress alloy sintering and insure the formation of small-sized intermetallic catalysts. The prepared optimal PtCo intermetallics as cathodic oxygen-reduction catalysts exhibit a high mass activity of 1.08 A mg Pt –1 at 0.9 V in H 2 -O 2 fuel cells and a rated power density of 1.17 W cm –2 in H 2 -air fuel cells. Synthesis of small sized Pt intermetallic catalysts remains challenging. Herewith authors prepared 18 binary Pt intermetallic compounds with small particle size by molecule-assisted synthesis strategy to in-situ form the heteroatom-doped carbon shell.

In this work, we preform a systematic investigation about hidden heavy and doubly heavy molecular states from the D ( ∗ ) D ¯ ( ∗ ) / B ( ∗ ) B ¯ ( ∗ ) and D ( ∗ ) D ( ∗ ) / B ¯ ( ∗ ) B ¯ ( ∗ ) interactions in the quasipotential Bethe–Salpeter equation (qBSE) approach. With the help of Lagrangians with heavy quark and chiral symmetries, interaction potentials are constructed within the one-boson-exchange model in which we include the π , η , ρ , ω and σ exchanges, as well as J / ψ or Υ exchange. Possible bound states from the interactions considered are searched for as the pole of scattering amplitude. The results suggest that experimentally observed states, Z c ( 3900 ) , Z c ( 4020 ) , Z b ( 10610 ) , and Z b ( 10650 ) , can be related to the D D ¯ ∗ , D ∗ D ¯ ∗ , B B ¯ ∗ , and B ∗ B ¯ ∗ interactions with quantum numbers I G ( J P ) = 1 + ( 1 + ) , respectively. The D D ¯ ∗ interaction is also attractive enough to produce a pole with 0 + ( 0 + ) which is related to the X (3872). Within the same theoretical frame, the existence of D D ¯ and B B ¯ molecular states with 0 ( 0 + ) are predicted. The possible D ∗ D ¯ ∗ molecular states with 0 ( 0 + , 1 + , 2 + ) and 1 ( 0 + ) and their bottom partners are also suggested by the calculation. In the doubly heavy sector, no bound state is produced from the D D / B ¯ B ¯ interaction while a bound state is found with 0 ( 1 + ) from D D ∗ / B ¯ B ¯ ∗ interaction. The D ∗ D ∗ / B ¯ ∗ B ¯ ∗ interaction produces three molecular states with 0 ( 1 + ) , 0 ( 2 + ) and 1 ( 2 + ) .

Carbon supported PtCo intermetallic alloys are known to be one of the most promising candidates as low-platinum oxygen reduction reaction electrocatalysts for proton-exchange-membrane fuel cells. Nevertheless, the intrinsic trade-off between particle size and ordering degree of PtCo makes it challenging to simultaneously achieve a high specific activity and a large active surface area. Here, by machine-learning-accelerated screenings from the immense configuration space, we are able to statistically quantify the impact of chemical ordering on thermodynamic stability. We find that introducing of Cu/Ni into PtCo can provide additional stabilization energy by inducing Co-Cu/Ni disorder, thus facilitating the ordering process and achieveing an improved tradeoff between specific activity and active surface area. Guided by the theoretical prediction, the small sized and highly ordered ternary Pt 2 CoCu and Pt 2 CoNi catalysts are experimentally prepared, showing a large electrochemically active surface area of ~90 m 2 g Pt ‒1 and a high specific activity of ~3.5 mA cm ‒2 . Platinum-based intermetallic alloys are promising candidates as low-platinum oxygen reduction reaction catalysts for proton exchange membrane fuel cells. Here, the authors develop small sized and highly ordered Pt 2 CoCu and Pt 2 CoNi catalysts for fuel cells by machine-learning accelerated computational screening.

Developing efficient and economical electrocatalysts for acidic oxygen evolution reaction (OER) is essential for proton exchange membrane water electrolyzers (PEMWE). Cobalt oxides are considered promising non-precious OER catalysts due to their high activities. However, the severe dissolution of Co atoms in acid media leads to the collapse of crystal structure, which impedes their application in PEMWE. Here, we report that introducing acid-resistant Ir single atoms into the lattice of spinel cobalt oxides can significantly suppress the Co dissolution and keep them highly stable during the acidic OER process. Combining theoretical and experimental studies, we reveal that the stabilizing effect induced by Ir heteroatoms exhibits a strong dependence on the distance of adjacent Ir single atoms, where the OER stability of cobalt oxides continuously improves with decreasing the distance. When the distance reduces to about 0.6 nm, the spinel cobalt oxides present no obvious degradation over a 60-h stability test for acidic OER, suggesting potential for practical applications. Dissolution of Co atoms in acidic media impedes the application of cobalt oxides in proton exchange membrane water electrolyzers. Here, the authors reveal a stabilizing effect induced by Ir single atoms on cobalt oxides that suppress Co dissolution.