Xinghua Su
材料科学技术（英文）
μSingle-crystal alpha alumina (α-Al2O3) platelets were synthesized by calcining a powder mixture of bayerite (α-Al(OH)3) and potassium sulfate (K2SO4) at 900°C. The crystalline phase evolutions and morphologies of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized samples mainly consisted of single-crystal α-Al2O3 platelets with a diameter of 0.5-1.5 μm and a thickness of 50-150 nm. Moreover, with 3, 5, and 8 wt% (referred to the obtained alumina) α-Al2O3 seeds adding into the powder mixture of bayerite and potassium sulfate, the average diameter of α-Al2O3 platelets can be reduced to 450, 240, and 220 nm, respectively. It is found that the sequence of the phase transformation is the bayerite (α-Al(OH)3) →boehmite (γ-AlOOH) →γ-Al2O3→α-Al2O3. Further analysis indicated that K2SO4 can promote the phase transformation from γ-Al2O3 to α-Al2O3 and the formation of single-crystal α-Al2O3 platelets might be attributed to the liquid phase K3Al(SO4)3.
关键词:
Alpha alumina
张广山
,
张文
,
陈勇生
,
王鹏
催化学报
doi:10.1016/S1872-2067(12)60675-5
研究了沉淀煅烧法制备的纳米级(CuAg)0.15In0.3Zn1.4S2光催化剂以及产氢效率,并采用X射线衍射、透射电镜、扫描电镜、N2吸附-脱附、紫外-可见吸收光谱等手段对催化剂进行了表征.结果表明,(CuAg)0.15In0.3Zn1.4S2的结晶度、比表面积和吸收可见光能力与煅烧温度和煅烧时间有关.在可见光下,以KI为电子给体,考察了不同条件对光催化产氢能力的影响.发现在600℃煅烧5h时所制的(CuAg)0.15Ir0.3Zn1.4S2光催化剂产氢活性最高,产氢速率为1750 μmol g-1 h-1,量子效率在420±5nm达到12.8％,比未煅烧催化剂的光催化活性提高了约6倍.
关键词:
光催化剂
,
多金属复合硫化物
,
制氢
,
煅烧
,
光催化活性
,
可见光
余运波
,
赵娇娇
,
韩雪
,
张燕
,
秦秀波
,
王宝义
催化学报
doi:10.1016/S1872-2067(11)60484-1
采用沉淀法制备了Co3O4,考察了焙烧和预处理条件对其结构、低温催化氧化CO性能的影响.热重分析表明,未经焙烧的样品以Co(OH)2CO3的形式存在,150～400℃空气气氛中焙烧后,样品以立方相Co3O4的形式存在.N2吸附-脱附法、X射线衍射、透射电镜及活性测试结果表明,以纳米颗粒物存在的Co3O4的比表面积、颗粒尺寸、催化氧化CO活性与焙烧温度密切相关.正电子湮没寿命谱、O2-程序升温脱附与定温条件下CO氧化测试结果表明,合适温度(150～250℃)下N2预处理有利于Co3O4表面氧空穴团的形成,它在吸附活化分子氧以及CO催化氧化反应中起到关键作用.同时讨论了预处理作用下Co3O4表面氧空穴的再构机制.
关键词:
四氧化三钴
,
焙烧
,
预处理
,
氧空穴
,
一氧化碳氧化
