Screening and Understanding Lattice Silicon-Controlled Catalytically Active Site Motifs from a Library of Transition Metal-Silicon Intermetallics

Multi-d Electron Synergy in LaNi1-x Cox Ru Intermetallics Boosts Electrocatalytic Hydrogen Evolution

Despite the fact that d-band center theory links the d electron structure of transition metals to their catalytic activity, it is yet unknown how the synergistic effect of multi-d electrons impacts catalytic performance. Herein, novel LaNi1-x Cox Ru intermetallics containing 5d, 4d, and 3d electrons were prepared. In these compounds, the 5d orbital of La transfers electrons to the 4d orbital of Ru, which provides adsorption sites for H*. The 3d orbitals of Ni and Co interact with the 5d and 4d orbitals to generate an anisotropic electron distribution, which facilitates the adsorption and desorption of OH*. The synergistic effect of multi-d electrons ensures efficient catalytic activity. The optimized LaNi0.5 Co0.5 Ru has an overpotential of 43mV at 10 mA cm-2 for alkaline electrocatalytic hydrogen evolution reaction. Beyond offering a variety of new electrocatalysts, this work reveals the multi-d electron synergy in promoting catalytic reaction.

Tuning Active Metal Atomic Spacing by Filling of Light Atoms and Resulting Reversed Hydrogen Adsorption-Distance Relationship for Efficient Catalysis

Precisely tuning the spacing of the active centers on the atomic scale is of great significance to improve the catalytic activity and deepen the understanding of the catalytic mechanism, but still remains a challenge. Here, we develop a strategy to dilute catalytically active metal interatomic spacing (dM-M) with light atoms and discover the unusual adsorption patterns. For example, by elevating the content of boron as interstitial atoms, the atomic spacing of osmium (dOs-Os) gradually increases from 2.73 to 2.96 Å. More importantly, we find that, with the increase in dOs-Os, the hydrogen adsorption-distance relationship is reversed via downshifting d-band states, which breaks the traditional cognition, thereby optimizing the H adsorption and H2O dissociation on the electrode surface during the catalytic process; this finally leads to a nearly linear increase in hydrogen evolution reaction activity. Namely, the maximum dOs-Os of 2.96 Å presents the optimal HER activity (8 mV @ 10 mA cm-2) in alkaline media as well as suppressed O adsorption and thus promoted stability. It is believed that this novel atomic-level distance modulation strategy of catalytic sites and the reversed hydrogen adsorption-distance relationship can shew new insights for optimal design of highly efficient catalysts.

Highly Active Si Sites Enabled by Negative Valent Ru for Electrocatalytic Hydrogen Evolution in LaRuSi

The discovery and identification of novel active sites are paramount for deepening the understanding of the catalytic mechanism and driving the development of remarkable electrocatalysts. Here, we reveal that the genuine active sites for the hydrogen evolution reaction (HER) in LaRuSi are Si sites, not the usually assumed Ru sites. Ru in LaRuSi has a peculiar negative valence state, which leads to strong hydrogen binding to Ru sites. Surprisingly, the Si sites have a Gibbs free energy of hydrogen adsorption that is near zero (0.063 eV). The moderate adsorption of hydrogen on Si sites during the HER process is also validated by in situ Raman analysis. Based on it, LaRuSi exhibits an overpotential of 72 mV at 10 mA cm^-2 in alkaline media, which is close to the benchmark of Pt/C. This work sheds light on the recognition of real active sites and the exploration of innovative silicide HER electrocatalysts.

d-sp orbital hybridization: a strategy for activity improvement of transition metal catalysts

Orbital hybridization to regulate the electronic structures and surface chemisorption properties of transition metals has been extensively investigated for searching high-performance catalysts toward various reactions. Unlike conventional d-d hybridization, the d-sp hybridization interaction between transition metals and p-block elements could result in surprising electronic properties and catalytic activities. This feature article highlights the recent progress in the development of high-performance transition metal-based catalysts through the extraordinary d-sp hybridization strategy, particularly for energy-related electrocatalytic applications. We start by giving an introduction of fundamental concepts associated with electronic structures of transition metal catalysts, including the Sabatier principle, d-band theory, electronic descriptor, as well as the comparison of d-d hybridization and d-sp hybridization strategies. Then, we summarize the theoretical and experimental advances in d-sp hybridization catalysts, including p-block element-doped metal catalysts, intermetallic catalysts and supported metal catalysts, with emphasis on the important roles of d-sp hybridization in tuning catalytic performances. Finally, we present existing challenges and future development prospects for the rational design of advanced d-sp hybridization catalysts.

Highly Dispersed Ru Nanoclusters Anchored on B, N Co-doped Carbon Nanotubes for Water Splitting

We developed an N, B co-doped carbon nanotubes as a substrate material to load 2-3 nm uniform Ru clusters. We rationally realized controllable N and B doping into carbon nanotubes....