Ultralow Pt Catalyst Loading Prepared by the Electroreduction of a Supramolecular Assembly for the Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) from the electrocatalysis of water splitting is the most promising approach to producing green and renewable hydrogen energy for sustainable development. The precious metal platinum is the best electrocatalyst for HER. However, its scarcity and high cost still hinder the large-scale application. It is highly desirable to fabricate efficient Pt electrocatalysts with low Pt loading. Herein, we report an efficient ultralow Pt-loading HER catalyst, which was obtained by the electroreduction of a preprepared supramolecular self-assembly. Utilizing the strong hydrogen bonding formation ability of macrocyclic cucurbit[8]uril (CB[8]), a porous supramolecule (CB[8]-[PtCl6]) composed of [PtCl6]2– and CB[8] is obtained as the HER catalyst precursor. By the electroreduction of the as-prepared supramolecular compound, Pt nanoparticles (NPs) protected by CB[8] (CB[8]-Pt) exhibit high catalytic activity and excellent long-term stability toward HER with ultralow Pt loading. CB[8]-Pt with a Pt loading of only 1.2 μg/cm2 presents 23 times higher HER activity than commercial Pt/C. Moreover, CB[8]-Pt shows excellent stability under 10 000-cycle cyclic voltammetry (CV) and at least 120 h for chronopotentiometry at 10 mA/cm2 in 0.5 M H2SO4, which greatly outperforms commercial Pt/C. This work provides a strategy for the rational design of ultralow-loading Pt catalysts with good activity and stability for hydrogen production

Steering CO₂ Electroreduction Selectivity U‑Turn to Ethylene by Cu–Si Bonded Interface

Copper (Cu), with the advantage of producing a deep reduction product, is a unique catalyst for the electrochemical reduction of CO2 (CO2RR). Designing a Cu-based catalyst to trigger CO2RR to a multicarbon product and understanding the accurate structure–activity relationship for elucidating reaction mechanisms still remain a challenge. Herein, we demonstrate a rational design of a core–shell structured silica-copper catalyst (p-Cu@m-SiO2) through Cu–Si direct bonding for efficient and selective CO2RR. The Cu–Si interface fulfills the inversion in CO2RR product selectivity. The product ratio of C2H4/CH4 changes from 0.6 to 14.4 after silica modification, and the current density reaches a high of up to 450 mA cm–2. The kinetic isotopic effect, in situ attenuated total reflection Fourier-transform infrared spectra, and density functional theory were applied to elucidate the reaction mechanism. The SiO2 shell stabilizes the *H intermediate by forming Si–O–H and inhibits the hydrogen evolution reaction effectively. Moreover, the direct-bonded Cu–Si interface makes bare Cu sites with larger charge density. Such bare Cu sites and Si–O–H sites stabilized the *CHO and activated the *CO, promoting the coupling of *CHO and *CO intermediates to form C2H4. This work provides a promising strategy for designing Cu-based catalysts with high C2H4 catalytic activity

Improving the Hydrogen Oxidation Reaction Rate of Ru by Active Hydrogen in the Ultrathin Pd Interlayer

Enhancing the catalytic activity of Ru metal in the hydrogen oxidation reaction (HOR) potential range, improving the insufficient activity of Ru caused by its oxophilicity, is of great significance for reducing the cost of anion exchange membrane fuel cells (AEMFCs). Here, we use Ru grown on Au@Pd as a model system to understand the underlying mechanism for activity improvement by combining direct in situ surface-enhanced Raman spectroscopy (SERS) evidence of the catalytic reaction intermediate (OHad) with in situ X-ray diffraction (XRD), electrochemical characterization, as well as DFT calculations. The results showed that the Au@Pd@Ru nanocatalyst utilizes the hydrogen storage capacity of the Pd interlayer to “temporarily” store the activated hydrogen enriched at the interface, which spontaneously overflows at the “hydrogen-deficient interface” to react with OHad adsorbed on Ru. It is the essential reason for the enhanced catalytic activity of Ru at anodic potential. This work deepens our understanding of the HOR mechanism and provides new ideas for the rational design of advanced electrocatalysts

What Elements Really Intercalate into Pd Lattice When Heated in Dimethylformamide?

Palladium hydrides (PdHx) are pivotal in both fundamental research and practical applications across a wide spectrum. PdHx nanocrystals, synthesized by heating in dimethylformamide (DMF), exhibit remarkable stability, granting them widespread applications in the field of electrocatalysis. However, this stability appears inconsistent with their metastable nature. The substantial challenges in characterizing nanoscale structures contribute to the limited understanding of this anomalous phenomenon. Here, through a series of well-conceived experimental designs and advanced characterization techniques, including aberration-corrected scanning transmission electron microscopy (AC-STEM), in situ X-ray diffraction (XRD), and time-of-flight secondary ion mass spectrometry (TOF-SIMS), we have uncovered evidence that indicates the presence of C and N within the lattice of Pd (PdCxNy), rather than H (PdHx). By combining theoretical calculations, we have thoroughly studied the potential configurations and thermodynamic stability of PdCxNy, demonstrating a 2.5:1 ratio of C to N infiltration into the Pd lattice. Furthermore, we successfully modulated the electronic structure of Pd nanocrystals through C and N doping, enhancing their catalytic activity in methanol oxidation reactions. This breakthrough provides a new perspective on the structure and composition of Pd-based nanocrystals infused with light elements, paving the way for the development of advanced catalytic materials in the future