Synergistic integration of Bi metal and phosphate defects on hexagonal and monoclinic BiPO4: Enhanced photocatalysis and reaction mechanism
Synergistic integration of Bi metal and phosphate defects on hexagonal and monoclinic BiPO4: Enhanced photocatalysis and reaction mechanism
复制标题
Bi金属和磷酸盐缺陷在六方和单斜BiPO4上的协同整合：增强的光催化和反应机制
DOI：
10.1016/j.apcatb.2018.10.055
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发表时间：
2019-04-01
影响因子：
22.1
通讯作者：
Dong, Fan
中科院分区：
文献类型：
--
作者：
Li, Jiarui;Zhang, Wendong;Dong, Fan
采用化学沉积法和溶剂热法分别制备了具有{102}面曝光的Bi六方相BiPO4(BiHBPO-102)和具有{120}面曝光的单斜相BiPO4(BiMBPO-120)。在可见光照射下，所制备的催化剂比纯BiPO4具有更高的光催化脱氮活性(BiPO4为2.0%，BiHBPO-102为51.4%，BiMBPO-120为36.2%)，这归因于磷酸盐缺陷、铋金属的表面等离子体共振(SPR)效应和小面效应的协同作用。用XPS和固态EPR技术证实了磷酸盐缺陷的存在。密度泛函计算揭示了磷酸盐的位置和磷酸盐缺陷在禁带内形成的中间能级，从而允许有效地将电荷从价带转移到导带。此外，铋金属将作为电子贡献者和电子导体，促进载流子的分离。因此，新的电荷转移路径可以被证明，因为共价环明显地产生在界面上，并沿着[Bi2O2](2+)->；铋金属->；PO43-的路径在Bi@BiPO4上产生。更重要的是，裸露{102}晶面的BiHBPO-102比裸露{120}晶面的BiMBPO-120具有更高的光催化活性。具有较强扭曲的PO4四面体和较低势垒(-17.5 eV)的{102}面上具有更有效的电荷转移的接触界面，促进了{102}面上活性自由基的产生。此外，对于Bi-HBPO-102，原位漂移可以观察到反应中间产物NO+，这有助于NO通过形成NO+而被活化，从而促进NOx氧化成最终产物。为此，我们开发了一种新的调节电荷转移路径的策略来提高光催化性能，并提出了一种新的光催化脱除NOx的反应机理。这一工作为光催化剂的改性和气相光催化反应机理的理解提供了新的思路。
Bi metal deposited hexagonal BiPO4 with the exposure of {102} facet (Bi-HBPO-102) and Bi metal deposited monoclinic BiPO4 with the exposure of {120} facet (Bi-MBPO-120) were prepared by chemical deposition method and solvothermal approach, respectively. The as-prepared catalysts presented more efficient photo catalytic activity of NO removal than pure BiPO4 (2.0% for BiPO4, 51.4% for Bi-HBPO-102 and 36.2% for Bi-MBPO-120) under visible light irradiation, which can be attributed to the synergistic effects endowed by the phosphate defect, the surface plasmon resonance (SPR) effect of Bi metal and the facet effect. The existence of phosphate defect was confirmed by the XPS and solid state EPR technique. The DFT calculation revealed the position of phosphate and the phosphate defect induced the formation of an intermediate level within the forbidden band to allow efficient charge transfer from valence band to conduction band. Moreover, the Bi metal would act as the electron contributor and electron conductor which facilitated the charge carriers separation. Therefore, a new charge transfer pathway can be certified on account of the fact that the covalent loop was evidently generated both at the interface and along with the path of [Bi2O2](2+) -> Bi metal -> PO43- on the Bi@BiPO4. More importantly, the Bi-HBPO-102 with exposure of {102} facet exhibited higher photocatalytic activity than the Bi-MBPO-120 with exposed {120} facet. The {102} facet with the stronger distorted PO4 tetrahedron and the lower potential energy barrier (-17.5eV) contributed to the contacted interface with the more efficient charge transfer, which promoted the generation of active radicals on {102} facet. Additionally, for Bi-HBPO-102, the reaction intermediate NO+ can be observed with in situ DRIFTS, which facilitated the activation of NO via the formation of NO+ to promote the oxidation of NOx into final products. Herein, a new strategy for tailoring the charge transfer pathway was developed to enhance the photocatalytic performance and a new photocatalytic reaction mechanism for photocatalytic NOx removal was proposed. This work could provide new insights into the modification of photocatalysts and mechanistic understanding of the gas-phase photocatalytic reaction mechanism.