Tuning the Selective Ethanol Oxidation on Tensile-Trained Pt(110) Surface by Ir Single Atoms

Development of efficient and robust electrocatalysts for complete oxidation of ethanol is critical for the commercialization of direct ethanol fuel cells. However, the complete oxidation of ethanol suffers from poor efficiency due to the low C1 pathway selectivity. Herein, single-atomic Ir (Ir₁ ) on hcp-PtPb/fcc-Pt core-shell hexagonal nanoplates (PtPb@PtIr₁ HNPs) enclosed by Pt(110) surface with a 7.2% tensile strain is constructed to drive complete electro-oxidation of ethanol. Benefiting from the construction of Ir₁ sites, the PtPb@PtIr₁ HNPs exhibit a Faraday efficiency of 57.93% for the C1 pathway, which is ≈8.3 times higher than that of the commercial Pt/C-JM. Furthermore, the PtPb@PtIr₁ HNPs show a top-ranked electro-activity achieving 45.1-fold and 56.3-fold higher than the specific and mass activities of Pt/C-JM, respectively. Meanwhile, the durability can be significantly enhanced by the construction of Ir₁ sites. Density functional theory calculations indicate that the strong synergy on the PtPb@PtIr₁ HNPs surface significantly promotes the breaking of CC bond of CH₂ CO* and facilitates CO oxidation and suppresses the deactivation of the catalyst. This work offers a unique single-atom approach using low-coordination active sites on shape-controlled nanocrystals to tune the selectivity and activity toward complicated catalytic reactions.

α-calcium sulfate hemihydrate with a 3D hierarchical straw-sheaf morphology for use as a remove Pb2+ adsorbent

Novel three-dimensional hierarchical α-calcium sulfate hemihydrate with a straw-sheaf morphology (3D α-HH straw-sheaves) are synthesized successfully in glycerin aqueous solution by a simple one-pot method, using as an efficient adsorbent for Pb²⁺ removal from water. The 3D straw-sheaf morphology, that closely depends on the glycerin/water volume ratio (V_Gly/V_H2O), can be accurately fabricated only when V_Gly/V_H2O is not lower than 3/1. 3D α-HH straw-sheaves are generated via multistep-splitting growth coupled with self-assembly. The obtained 3D α-HH straw-sheaves are further used as an adsorbent to remove Pb²⁺ from water, exhibiting excellent Pb²⁺ removal performance with an equilibrium adsorption capacity of 79.19 mg_Pbg_α-HH^-1 and removal efficiency of 98.98%, that both higher than those of plate- and columnar-like α-HH. Moreover, the experimental adsorption data for the 3D α-HH straw-sheaves is well fitted with pseudo-second-order kinetic model, and the adsorption isotherm is in good agreement with Langmuir model. The Pb²⁺ adsorption mechanism is thought to be a chemical adsorption process enforced by chemical bonding and ion exchange. This work demonstrates that 3D α-HH straw-sheaves are highly promising in removing Pb²⁺ from wastewater, thereby broadening the research field for the practical application of gypsum-based materials.

Highly Porous Pt2Ir Alloy Nanocrystals as a Superior Catalyst with High-Efficiency C-C Bond Cleavage for Ethanol Electrooxidation

Achieving high catalytic performance with high CO₂ selectivity is critical for commercialization of direct ethanol fuel cells. Here, we report carbon-supported highly porous Pt₂Ir alloy nanocrystals (p-Pt₂Ir/C) for an ethanol oxidation reaction (EOR) that displays nearly 7.2-fold enhancement in mass activity and promotes antipoisoning ability and durability for the EOR as compared with the commercial Pt/C-JM. Moreover, the catalyst exhibits high CO₂ selectivity, 3.4-fold at 0.65 V (vs. SCE) and 4.1-fold at 0.75 V (vs. SCE) higher as compared with the carbon-supported porous Pt nanocrystals (p-Pt/C). The highly porous structure is composed of interconnected one-dimensional (1D) rough branches with an average diameter of only 1.9 nm, largely promoting Pt utilization efficiency and accelerating mass transfer. The 1D rough branch surface exposed many atomic steps/corners endowed with abundant high activity sites. Alloying with Ir can significantly improve the antipoisoning ability, durability, and C-C bond cleavage ability, thereby evidently enhancing its EOR performance.

Porous Noble Metal Electrocatalysts: Synthesis, Performance, and Development

Active sites (intrinsic activity, quantity, and distribution), electron transfer, and mass diffusion are three important factors affecting the performance of electrocatalysts. Composed of highly active components which are built into various network structures, porous noble metal is an inherently promising electrocatalysts. In recent years, great efforts have been made to explore new efficient synthesis methods and establish structural-performance relationships in the field of porous noble metal electrocatalysis. In this review, the very recent progress in strategies for preparing porous noble metal, including innovation and deeper understanding of traditional methods is summarized. A discussion of relationship between porous noble metal structure and electrocatalytic performance, such as accessibility of active sites, connectivity of skeleton structures, channels dimensions, and hierarchical structures, is provided.