LaTiO 2 N has been considered a promising candidate for efficient photocatalytic water splitting. However, its photocatalytic activity is often hampered by the presence of structural defects and poor charge mobility. In this work, we introduced Ca into the crystal structure of LaTiO 2 N via a simple co-precipitation method and investigated the photocatalytic and photoelectrochemical properties for the full range solid solution La 1− x Ca x TiO 2+ y N 1−y (0 ⩽ x , y ⩽ 1). Our results show that incorporating Ca into LaTiO 2 N induces a strong structural shrinkage as well as a space group change from I mma to P nma around a middle doping point ( x = 0.5). The presence of Ca effectively boosts the photocatalytic oxygen production and aids photocurrent extraction for LaTiO 2 N. The best photocatalytic activity was achieved for sample La 0.3 Ca 0.7 TiO 2.7 N 0.3 with oxygen production rate ∼66.96 μmol/h under visible light illumination ( λ ⩾ 420 nm), corresponding to apparent quantum efficiency ∼3.13%. XPS analysis revealed a substantial reduction in surface Ti 3+ species and a removal of A-site cation segregation for samples containing Ca. Further photoelectrochemical analysis highlights the critical role of Ca in enhancing the charge mobility of LaTiO 2 N. The better photocatalytic performance of Ca-modified LaTiO 2 N can be understood as a result of defect removal, high charge mobility, and improved surface charge migration pathways that considerably prolong the lifetimes of photogenerated charges.
Jun Zhang,Yaoxin Xiao,Rui Shan,Haoran Yuan,Yong Chen
In the present research, calcium decorated copper@nitrogen-doped carbon (marked as Cu 1 Ca x @CN) derived from biomass was constructed for highly selective hydrogenation of bio-based furfural (FFR), which remarkably favored furan ring hydrogenation for tetrahydrofurfuryl alcohol (THFA) formation via regulating the hydrogenation path. Remarkably, the in-situ generated basic sites from N- and Ca-containing species were beneficial to the good metal dispersion as well as the chemical activation of aldehyde and C=C groups, thus favoring the FFR-to-THFA transformation. The optimal basic density-to-copper mass ratio in a range of 3.0 ∼ 4.0 was attained, in consideration of THFA generation. The as-prepared Cu 1 Ca 0.87 @CN catalyst could afford full FFR conversion as well as 75.6 % THFA yield under 3 MPa H 2 atmosphere, which also exhibited excellent stability and could be recycled four times without any deactivation. In addition, the basic sites in the as-prepared Cu 1 Ca x @CN samples were capable of activating both the C=O and C=C bonds, and the activation of C=O bond took precedence over that of C=C bond, especially in the case of relative low temperatures. Plausible reaction mechanism for FFR-to-THFA transformation under the synergistic effect of active Cu 0 center and basic sites was proposed in detail.
Discharging phosphorus (P)-contaminated water directly into the aquatic environment leads to resource loss and eutrophication . Thus, removing P from waste streams is imperative. In this study, calcium-decorated biochar (Ca-BC) in different mass ratios of Ca to BC was designed to effectively adsorb P from solution. Ca-BC was characterized through X-ray diffraction (XRD) analysis, followed by isotherm and kinetic adsorption experiments. The decorated Ca on the BC surface was found to have preferred P adsorption ability. A design of calcium hydroxide (Ca(OH) 2 ) to flour in a mass ratio of 2:1 was found to have a maximum adsorption capacity of 314.22 mg g −1 for P. The Langmuir and pseudo-second-order models fit the sorption process adequately. XRD analysis indicated that the preferable adsorption ability to P was due to the reaction of Ca(OH) 2 and PO 4 3− , forming the hydroxylapatite (Ca 5 (PO 4 ) 3 (OH)) crystal. The P in solution was transformed to the crystal. Thus, Ca-BC is an environmental friendly and low-cost sorbent for P removal.
危险品化学品经营许可证（带存储）