Interfaces Engineering of Ultrafine Ni@Ni2P/C Core-Shell Heterostructure for High Yield Hydrogen Peroxide Electrosynthesis.

Developing cost-effective and sustainable catalysts with exceptional activity and selectivity is essential for the practical implementation of on-site H2O2 electrosynthesis, yet it remains a formidable challenge. Metal phosphide core-shell heterostructures anchored in carbon nanosheets (denoted as Ni@Ni2P/C NSs) are designed and synthesized via carbonization and phosphidation of the 2D Ni-BDC precursor. This core-shell nanostructure provides more accessible active sites and enhanced durability, while the 2D carbon nanosheet substrate prevents heterostructure aggregation and facilitates mass transfer. Theoretical calculations further reveal that the Ni/Ni2P heterostructure-induced optimization of geometric and electronic structures enables the favored adsorption of OOH* intermediate. All these features endow the Ni@Ni2P/C NSs with remarkable performance in 2e ORR for H2O2 synthesis, achieving a top yield rate of 95.6 mg L-1 h-1 with both selectivity and Faradaic efficiency exceeding 90% under a wide range of applied potentials. Furthermore, when utilized as the anode of an assembled gas diffusion electrode (GDE) device, the Ni@Ni2P/C NSs achieve in situ H2O2 production with excellent long-term durability (>32 h). Evidently, this work provides a unique insight into the origin of 2e ORR and proposes optimization of H2O2 production through nano-interface manipulation.

Efficient preparation of carbon nanospheres-anchored porous carbon materials and the investigation on pretreatment methods.

Manufacturing high-performance activated carbon (AC) materials from abundant biomass at low temperature and short activation time is targeted by the green and sustainable chemical industry. Here, a 1980 m2/g of carbon nanospheres-anchored porous carbon material (PHAC) derived from waste sawdust was prepared by a method of H3PO4 hydrothermal combined with fast activation at 450 °C within 2.8 min. It is found that H3PO4 hydrothermal pretreatment could promote the dehydration of carbohydrates to form more unstable C = O structures, which were decomposed in the subsequent fast activation to form pore structures. In addition, this process is also conducive to the formation of carbon nanospheres, increasing the degree of graphitization and producing more graphite defects. The prepared PHAC showed good adsorption performance for different types of pollutants. This work provides a new insight for the preparation of high performance biomass based carbon materials under mild conditions.

Colloidal dispersion stability of unilamellar DPPC vesicles in aqueous electrolyte solutions and comparisons to predictions of the DLVO theory.

The colloidal dispersion stability at 25 degrees C of aqueous dispersions of sonicated DPPC (dipalmitoylphosphatidylcholine) vesicles was quantitatively evaluated from the Fuchs-Smoluchowski stability ratio W. Data of average particle size vs. time were obtained with dynamic light scattering measurements. Dispersions in water, 1, 10, or 150mM aqueous sodium chloride, and phosphate buffer saline (PBS) solutions were tested. The W-values ranged from about 8x10(6) to 6x10(8). The dispersed particles had small but significant zeta-potentials zeta, implying that the vesicles had some significant charge due to preferential adsorption of negative hydroxyl ions over hydronium ions in water, and chloride ions over sodium ions in the electrolyte solutions. Hence, there was some contribution of the double-layer electrostatic forces to the dispersion stability. The initial values of zeta ranged from -30 to 8mV. The vesicle non-retarded Hamaker constants were estimated from the published values of the Hamaker constants of DPPC and water in vacuum, and they varied with the vesicle size. A new dimensionless model of the DLVO theory for spherical particles was formulated, focusing on the conditions for the existence of a positive interaction potential energy maximum, Phi(max), which is linked to W. The dimensionless number N, which is defined as the ratio of the electric double layer energy to the Hamaker constant A, was found to be the key determinant of Phi(max) and W. DLVO calculations of Phi(max), and W with error analysis show that the charged DPPC vesicles tested are quite more stable than predicted. This discrepancy highlights some significant weaknesses in the premises and approximations of the DLVO theory, and the need for improved theories, possibly considering other repulsive forces.