Bimetallic palladium-copper nanoplates with optimized d-band center simultaneously boost oxygen reduction activity and methanol tolerance

Universal synthesis of highly active PdM (Sb, Ir, and Bi) nanowire networks for ethylene glycol and glycerol electrooxidation

One-dimensional (1D) Pd-based nanowire materials, characterized by high aspect ratios and exposed high-index crystal surfaces, are widely developed in the field of direct fuel cells. However, their synthesis methods are often not universal and necessitate demanding conditions, including high temperatures and metal templates, leading to resource consumption. In this study, we present a simple and universal one-step method for synthesizing PdM (Sb, Ir, and Bi) nanowire networks (NNWs) at room temperature. Leveraging their structural advantages and the synergistic effects between bimetals, PdM NNWs demonstrate exceptional electrocatalytic performance, exhibiting higher mass and specific activities as well as enhanced durability compared to Pd/C for the ethylene glycol and glycerol oxidation reactions. Notably, PdSb NNWs excelled in electrochemical tests, achieving the highest mass activities of 7.55 and 5.59 A mg-1 for the ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR), respectively. Additionally, due to the semi-metallic properties of Sb, which can flexibly modify the chemical environment of Pd, the PdSb NNWs exhibited superior antitoxicity and a significantly lower decay of current density across three consecutive chronoamperometry (CA) tests. This research advances the synthesis of palladium-based nanostructures, providing impetus for the design of highly efficient electrocatalysts in the realm of direct alcohol fuel cells.

Cyanogel-Transformed Porous Palladium and Iron Framework Intermixed with rGO for Wearable Hydrogen Sensing

Wearable hydrogen (H2) sensing is necessary to monitor the H2 leakage in its transportation and storage, of which ppm-concentration detection limit and fast response at room temperature are highly desired. Here, a wearable H2 sensing working at room temperature is developed with palladium and iron framework intermixed with reduced graphene oxide (rGO//Pd-Fe FW), which is synthesized by combined Pd-Fe cyanogel immobilized with graphene oxide as precursor and in situ reduction. As-prepared rGO//Pd-Fe FW is observed with porous FW structure composed of interconnected Pd-Fe nanoparticles, in which rGO is evenly intermixed. Beneficially, rGO//Pd-Fe FW exhibits 2 ppm low detection limit and 2 s fast response (1 v/v% H2) at room temperature. Such excellent H2 sensing performance may be attributed to the synergistic effect of the optimized Pd-Fe FW's catalytic activity, boosted electron transfers between Pd hydride and rGO, and enriched adsorption sites over porous FW's surface. Practically, the perceptron learning algorithm combined with principal component analysis is conducted to identify the H2 leakage, and the wearable H2 sensing devices are built by integrating rGO//Pd-Fe FW over the paper and flexible printed circuit board with reliable sensing responses.

Solvothermal synthesis of PdCu nanorings with high catalytic performance for alcohol electrooxidation

Two-dimensional (2D) Pd-based nanostructures with a high active surface area and a large number of active sites are commonly used in alcohol oxidation research, whereas the less explored ring structure made of nanosheets with large pores is of interest. In this study, we detail the fabrication of PdCu nanorings (NRs) featuring hollow interiors and low coordinated sites using a straightforward solvothermal approach. Due to increased exposure of active sites and the synergistic effects of bimetallics, the PdCu NRs exhibited superior catalytic performance in both the ethanol oxidation reaction (EOR) and the ethylene glycol oxidation reaction (EGOR). The mass activities of PdCu NRs for EOR and EGOR were measured at 7.05 A/mg and 8.12 A/mg, respectively, surpassing those of commercial Pd/C. Furthermore, the PdCu NRs demonstrated enhanced catalytic stability, maintaining higher mass activity levels compared to other catalysts during stability testing. This research offers valuable insights for the development of efficient catalysts for alcohol oxidation.

Decorating Pd-Au Nanodots Around Porous In2O3 Nanocubes for Tolerant H2 Sensing Against Switching Response and H2S Poisoning

With the recently-booming hydrogen (H2) economy by green H2 as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H2 as a biomarker, H2 sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H2 sensing has been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/In2O3 NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/In2O3 NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/In2O3 NCBs show 300 ppb-low detection limit, 5 s-fast response to 500 ppm H2, 75%RH-high humidity tolerance, and 56 days-long stability at 280 °C. Further, Pd-Au NDs/In2O3 NCBs show excellent stability against switching sensing response, and are tolerant to H2S poisoning even being exposed to 10 ppm H2S at 280 °C. Such excellent H2 sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H2 and H2S. Practically, Pd-Au NDs/In2O3 NCBs are integrated into the H2 sensing device, which can reliably communicate with a smartphone.

WCx-Supported RuNi Single Atoms for Electrocatalytic Oxygen Evolution

Single-atom catalysts anchored to oxide or carbonaceous substances are typically tightly coordinated by oxygen or heteroatoms, which certainly impact their electronic structure and coordination environment, thereby affecting their catalytic activity. In this study, we prepared a stable oxygen evolution reaction (OER) catalyst on tungsten carbide using a simple pyrolysis method. The unique structure of tungsten carbide allows the atomic RuNi catalytic site to weakly bond to the surface W and C atoms. XRD patterns and HRTEM images of the WCx-RuNi showed the characteristics of phase-pure WC and W2C, and the absence of nanoparticles. Combined with XPS, the atomic dispersion of Ru/Ni in the catalyst was confirmed. The catalyst exhibits excellent catalytic ability, with a low overpotential of 330 mV at 50 mA/cm2 in 1 m KOH solutions, and demonstrates high long-term stability. This high OER activity is ascribed to the synergistic action of metal Ru/Ni atoms with double monomers. The addition of Ni increases the state density of WCx-RuNi near the Fermi level, promoting the adsorption of oxygen-containing intermediates and enhancing electron exchange. The larger proximity of the d band center to the Fermi level suggests a strong interaction between the d electrons and the valence or conduction band, facilitating charge transfer. Our research offers a promising avenue for reasonable utilization of inexpensive and durable WCx carrier-supported metal single-atom catalysts for electrochemical catalysis.