Rare-Earth Substitution Induced Symmetry Breaking for The First Sc-Based Nonlinear Optical Chalcogenide with High-Performance.

Chalcogenides are the most important infrared nonlinear optical (NLO) material candidates, and the exploration of high-performance ones is attractive and challengeable. Hitherto, there is no NLO scandium (Sc) chalcogenides experimentally studied. Here, new quaternary Sc thiophosphate CsScPS (CSPS) was synthesized by the facile metal oxide-boron-sulfur/reactive flux hybrid solid-state method.

Correlation between d Electrons and the Sweet Spot for the Hydrogen Evolution Reaction: Is Platinum Always the Best Electrocatalyst?

Herein, two Laves intermetallic series, ZrCo and NbCo ( = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt), were synthesized, and their hydrogen evolution reaction (HER) activities were examined to reveal the influence of d electrons to the corresponding HER activities. Owing to the different electronegativity between Zr and Nb (χ = 1.33; χ = 1.

Direct Electrosynthesis of Metal Nanoparticles on TiCT-Mxene during Hydrogen Evolution.

Herein, we propose a simple yet effective method to deposit metal nanoparticles on TiCT-MXene via direct electrosynthesis. Without using any reducing reagent or annealing under reducing atmosphere, it allows the conversion of metal salts (e.g.

In situ X-ray spectroscopies beyond conventional X-ray absorption spectroscopy on deciphering dynamic configuration of electrocatalysts.

Realizing viable electrocatalytic processes for energy conversion/storage strongly relies on an atomic-level understanding of dynamic configurations on catalyst-electrolyte interface. X-ray absorption spectroscopy (XAS) has become an indispensable tool to in situ investigate dynamic natures of electrocatalysts but still suffers from limited energy resolution, leading to significant electronic transitions poorly resolved. Herein, we highlight advanced X-ray spectroscopies beyond conventional XAS, with emphasis on their unprecedented capabilities of deciphering key configurations of electrocatalysts.

Regulating Intramolecular Electron Transfer of Nickel-Based Coordinations through Ligand Engineering for Aqueous Batteries.

The integration of electronic effects into complexes for the construction of novel materials has not yet attracted significant attention in the field of energy storage. In the current study, eight one-dimensional (1D) nickel-based salicylic acid  complexes (Ni-XSAs, X = pH, pMe, pMeO, mMe, pBr, pCl, pF, and pCF ), are prepared by ligand engineering. The coordination environments in the Ni-XSAs are explored using X-ray absorption fine structure spectroscopy.

A step-by-step strategy to design active and stable quaternary intermetallic compounds for the hydrogen evolution reaction.

Multinary intermetallic compounds with rich chemical compositions enable one to achieve a logical design for desired materials based on the required function. In this work, we have demonstrated a step-by-step strategy to design a quaternary intermetallic compound that exhibits highly active and stable performance for the hydrogen evolution reaction (HER). With binary intermetallic TaCo as the starting point, the minor inclusion of a ductile Cu element in TaCo to form ternary TaCuCo can substantially lower the degradation rate from 20% to 5% after sintering treatment (, enhance connectivity between particles).

Balance between Activity and Stability of Single Metal and Intermetallic Compounds for Electrocatalytic Hydrogen Evolution Reaction.

The higher population of the antibonding state around the Fermi level will result in better activity yet lower stability of HER (Re vs Ru metal). There seems to be a limitation or balance for using a single metal since the bonding scheme of a single metal is relatively simple. Combining Re (strong bonding), Ru (HER active), and Zr metal (corrosion-resistant) grants ternary intermetallic compound ZrReRu, exhibiting excellent HER activity and stability in acidic and alkaline electrolytes.

Spatially and temporally understanding dynamic solid-electrolyte interfaces in carbon dioxide electroreduction.

The ubiquity of solid-liquid interfaces in nature and the significant role of their atomic-scale structure in determining interfacial properties have led to intensive research. Particularly in electrocatalysis, however, a molecular-level picture that clearly describes the dynamic interfacial structures and organizations with their correlation to preferred reaction pathways in electrochemical reactions remains poorly understood. In this review, CO electroreduction reaction (CORR) is spatially and temporally understood as a result of intricate interactions at the interface, in which the interfacial features are highly relevant.

2D MOF-assisted Pyrolysis-displacement-alloying Synthesis of High-entropy Alloy Nanoparticles Library for Efficient Electrocatalytic Hydrogen Oxidation.

Multimetallic alloy nanoparticles (NPs) have received considerable attention in various applications due to their compositional variability and exceptional properties. However, the complexity of both the general synthesis and structure-activity relationships remain the long-standing challenges in this field. Herein, we report a versatile 2D MOF-assisted pyrolysis-displacement-alloying route to successfully synthesize a series of binary, ternary and even high-entropy NPs that are uniformly dispersed on porous nitrogen-doped carbon nanosheets (PNC NSs).

Dual Function of Hypo-d-electronic Transition Metals in the Brewer Intermetallic Phase for the Highly Efficient Electrocatalytic Hydrogen Evolution Reaction in Alkaline Electrolytes.

Reported are the synthesis, material characterization, and electrocatalytic hydrogen evolution reaction (HER) in acid and alkaline electrolytes for the Brewer intermetallic phase, NbCo and MoCo. It was realized that the overpotential at a current density of 10 mA/cm (η) for NbCo (η = 62 mV) and MoCo (η = 143 mV) are both much lower than that of using a single Co metal (η = 253 mV) in alkaline electrolytes. The enhancement of electrocatalytic HER activity of NbCo and MoCo can be attributed to the hypo-hyper-d-electronic interaction between Nb/Mo and Co elements.

Function of Internal and External Fe in a Ni-Based Precatalyst System Toward Oxygen Evolution Reaction.

It is well known that the "iron" impurity will influence the oxygen evolution reaction (OER) in an alkaline electrolyte, especially for the Ni-based electrocatalyst. Many research studies have investigated the function of Fe in the OER active phase, such as (OH)/OOH ( = Ni and/or Fe), while, surprisingly, very few studies have examined the function of Fe in the "precatalyst" system. Accordingly, in this work, the NiFeP ( = 0, 0.

Exploring the synergistic effect of alloying toward hydrogen evolution reaction: a case study of NiM (M = Ti, Ge and Sn) series.

In this work, we have demonstrated that one can control the intrinsic activity of Ni metal toward the hydrogen evolution reaction (HER) by simply alloying Ni with different elements ( Ti, Ge or Sn). The HER activities of NiM (M = Ti, Ge and Sn) series and Ni metal follow the order of NiTi ( = 68 mV) > NiSn ( = 122 mV) > NiGe ( = 161 mV) > Ni ( = 273 mV). After normalizing their HER performances based on the roughness factor (RF), it was realized that NiTi and NiSn both exhibit higher intrinsic HER activities than that of Ni metal while NiGe displays the worst HER performance.

Function of Doping Ru Element in the Hydrogen Evolution Reaction in Rare-Earth Transition-Metal Intermetallics.

Transition metal-based intermetallics are promising electrocatalysts for replacing the commercial Pt metal in the hydrogen evolution reaction (HER). In this work, RENi and RERuNi (RE = Pr, Tb, and Er) were synthesized and their electrocatalytic HER activities were explored. Among undoped compounds, PrNi exhibits the best performance and requires an overpotential of 55 mV, while partially replacing Ni with Ru element (PrRuNi) can greatly reduce the overpotential to 20 mV at a current density of 10 mA/cm.

Crystal and Electronic Structure Modification of Synthetic Perryite Minerals: A Facile Phase Transformation Strategy to Boost the Oxygen Evolution Reaction.

Geometry effect and electronic effect are both essential for the rational design of a highly efficient electrocatalyst. In order to untangle the relationship between these effects and electrocatalytic activity, the perryite phase with a versatile chemical composition, (NiFe)(P) ( = Si and Ge; 1 ≥ , ≥ 0), was selected as a platform to demonstrate the influence of geometry (e.g.

Crystal and electronic structure manipulation of Laves intermetallics for boosting hydrogen evolution reaction.

Since the 1970s, Laves intermetallics (AB) have been widely used in hydrogen storage technology (e.g., nickel-metal hydride batteries) due to the abundant interstitial sites and moderate metal-hydrogen bond strength (E).

Synthesis, Crystal Structure, Electronic Structure, and Electrocatalytic Hydrogen Evolution Reaction of Synthetic Perryite Mineral.

Recently, it has been reported that the enstatite chondrite (EC) meteorite may contain enough hydrogen to provide a plausible explanation for water's initial existence on Earth. Perryite mineral is one of the key components of EC, but its detailed chemical composition and phase width remain elusive compared with other minerals found in EC. Therefore, we embark on a series of investigations of the synthesis, crystal structure, and electronic structure of the synthetic perryite mineral (NiFe)(P) ( = Si and Ge; 1 ≥ , ≥ 0).

Lanthanide contraction regulates the HER activity of iron triad intermetallics in alkaline media.

In this work, we have systematically investigated the HER activity of the RECo (RE = Y, Pr, Gd, Tb, Ho and Er) series and revealed that their HER activities are highly correlated with the averaged Co-Co bond length of each compound. The HER performance follows the order of GdCo > TbCo > PrCo > YCo > HoCo > ErCo. This suggests that the unique feature of rare-earth metals, lanthanide contraction, can effectively alter the interatomic spacing and impact the corresponding HER activity.

Electronic structure inspired a highly robust electrocatalyst for the oxygen-evolution reaction.

We demonstrated that the electronic-band structure holds the key to electrocatalytic durability towards the oxygen-evolution reaction (OER). Density functional theory (DFT) revealed the characteristic of Ni-Ni bonding interactions within NiP, NiP and NiP were different and could influence their phase stabilities during the OER. NiP and NiP exhibited very robust OER performances at high current density (>350 mA cm) over 12 h whereas, for NiP, obvious deterioration was observed.

Intermetallic compounds with high hydrogen evolution reaction performance: a case study of a MCo (M = Ti, Zr, Hf and Sc) series.

Noble metals (e.g., Ru, Ir and Pt) or their derivatives exhibit very appealing activity toward the hydrogen evolution reaction (HER), but their high price and low reserves impede their wide use.

Partial substitution induced centrosymmetric to noncentrosymmetric structure transformation and promising second-order nonlinear optical properties of (KBa)GaSe.

Partial substitution of Ba by K in the Ba sites of BaGa2Se4 creates a new selenide (K0.38Ba0.81)Ga2Se4 (1), which is crystallized in the noncentrosymmetric space group I4cm, different from the centric structures of all the ternary MI-MIII2-Q4 (MII = divalent Sr, Ba, Pb, Sn, Eu; MIII = trivalent Ga, In; Q = S and Se) chalcogenides.

Partial Congener Substitution Induced Centrosymmetric to Noncentrosymmetric Transformation Witnessed by KGa(GeM)Se (M = Si, Sn) and Their Nonlinear Optical Properties.

Crystallizing in a noncentrosymmetric (NCS) structure is the essential requirement for a crystal to be second-order nonlinear optical (NLO) active. Here, a simple strategy of partial congener substitution is introduced to induce transformation of the known centrosymmetric KGaGeSe (2/) to the new isostructural NCS species KGa(GeSn)Se () and KGa(GeSi)Se () (). Their structures feature a {[Ga(GeM)Se]} (M = Si, Sn) polyanionic framework built from the basic functional motif M'Se (M' = Ga, Ge, M) tetrahedra, similar to but slightly distorted from that of KGaGeSe.

Electrochemical Hydrogen Evolution Reaction Efficiently Catalyzed by Ru P Nanoparticles.

Developing alternatives to Pt catalysts is a prerequisite to cost-effectively produce hydrogen. Herein, we demonstrate Ru P nanoparticles (without any doping and modifications) as a highly efficient Pt-like catalyst for the hydrogen evolution reaction (HER) in different pH electrolytes. On transferring the hexagonal close-packed crystal structure of Ru to the orthorhombic structure of Ru P, a greatly improved catalytic activity and stability toward HER is found owing to Ru-P coordination.

Crystal Chemistry and Photocatalytic Properties of RESTe (RE = Gd, Ho, Er, Tm): Experimental and Theoretical Investigations.

Reported are the synthesis and structural characterization of a new series of ternary rare-earth mix-chalcogenides RESTe (RE = Gd, Ho, Er, Tm) that have been obtained from high-temperature solid state reactions. These compounds crystallize in HoSTe structure types with monoclinic C2/ m and/or orthorhombic Immm space groups. The space group variation within this series is due to the position disorder along the Te plane (Te to TeA and TeB).

Intricate Li-Sn Disorder in Rare-Earth Metal-Lithium Stannides. Crystal Chemistry of RELiSn (RE = La-Nd, Sm; x < 0.3) and EuLiSn ( x ≈ 2.0).

Reported are the syntheses, crystal structures, and electronic structures of six rare-earth metal-lithium stannides with the general formulas RELiSn (RE = La-Nd, Sm) and EuLiSn. These new ternary compounds have been synthesized by high-temperature reactions of the corresponding elements. Their crystal structures have been established using single-crystal X-ray diffraction methods.