Boosting Li-O2 Battery Performance via Coupling of P-N Site-Rich N, P Co-Doped Graphene-Like Carbon Nanosheets with Nano-CePO4.

Development of efficient and robust cathode catalysts is critical for the commercialization of Li-O2 batteries (LOBs). Herein, a well-designed CePO4 @N-P-CNSs cathode catalyst for LOBs via coupling P-N site-rich N, P co-doped graphene-like carbon nanosheets (N-P-CNSs) with nano-CePO4 via a novel "in situ derivation" coupling strategy by in situ transforming the P atoms of P-C sites in N-P-CNSs to CePO4 is reported. The CePO4 @N-P-CNSs exhibit superior bifunctional ORR/OER activity relative to commercial Pt/C-RuO2 with an overall overpotential of 0.64 V (vs RHE). Moreover, the LOB with CePO4 @N-P-CNSs as the cathode catalyst delivers a low charge overpotential of 0.67 V (vs Li/Li+ ), high discharge capacity of 29774 mAh g-1 at 100 mA g-1 and long cycling stability of 415 cycles, respectively. The remarkably enhanced LOB performance is attributable to the in situ derived CePO4 nanoparticles and the P-N sites in N-P-CNSs, which facilitate increased bifunctional ORR/OER activity, promote the rapid and effective decomposition of Li2 O2 and inhibit the formation of Li2 CO3 . This work may provide new inspiration for designing efficient, durable, and cost-effective cathode catalysts for LOBs.

Activating Pd Nanoparticles on Oxygen-Doped g-C3N4 for Visible Light-Driven Thermocatalytic Oxidation of Benzyl Alcohol.

Direct oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using O2 as the oxidant has crucial significance under mild conditions in industrial manufacturing. Herein, an efficient and ecofriendly Pd/O-g-C3N4 heterojunction catalyst using oxygen-doped g-C3N4 (O-g-C3N4) with a porous surface as the support is developed for visible light-driven thermocatalytic oxidation of BzOH to BzH by using O2 as the sole oxidant. The obtained Pd/O-g-C3N4 exhibits visible light-enhanced catalytic performance under visible light irradiation with BzOH conversion and BzH yield of 89.4 and 76.6%, respectively, which are 1.96 and 1.83 times higher than those for the catalyst in the dark. Oxygen doping, as well as Pd deposition, can significantly narrow the band gap of g-C3N4, thereby enhancing its visible light harvesting ability. The resulting heterojunction interface between Pd nanoparticles and O-g-C3N4 might promote separation of the photogenerated e--h+ pairs. In addition to achieving considerable BzOH conversion and BzH yield, Pd/O-g-C3N4 also exhibits impressive stability. The current study provides potential applications for the green and efficient catalytic oxidation of other alcohols to corresponding aldehydes using O2 as the oxidant.

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 (VGly/VH2O), can be accurately fabricated only when VGly/VH2O 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 mgPbgα-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.

Ordered PdCu-Based Core-Shell Concave Nanocubes Enclosed by High-Index Facets for Ethanol Electrooxidation.

Crystal phase engineering is a powerful strategy for regulating the performance of electrocatalysts toward many electrocatalytic reactions. Herein we demonstrate that Au@Pd1Cu concave nanocubes (CNCs) with an ordered body-centered cubic (bcc) PdCu alloy shell enclosed by many high active high-index facets can be adopted as highly active yet stable electrocatalysts for the ethanol oxidation reaction (EOR). These CNCs are more efficient than other nanocrystals with a disordered face-centered cubic (fcc) PdCu alloy surface and display high mass and specific activities of 10.59 A mgpd-1 and 33.24 mA cm-2, which are 11.7 times and 4.1 times higher than those of commercial Pd black, respectively. Our core-shell CNCs also exhibit robust durability with the weakest decay in activity after 250 potential-scanning cycles, as well as outstanding antipoisoning ability. Alloying with Cu and the ordered bcc phase surface can provide abundant OHads species to oxidize carbonaceous poison to avoid catalyst poisoning, and the exposed high-index facets on the surface can act as highly catalytic sites.