Low temperature synthesis of mesoporous boron carbides as metal-free photocatalysts for enhanced CO2 reduction and generation of hydroxyl radicals
Low temperature synthesis of mesoporous boron carbides as metal-free photocatalysts for enhanced CO2 reduction and generation of hydroxyl radicals
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低温合成介孔碳化硼作为无金属光催化剂，用于增强二氧化碳还原和羟基自由基的产生
DOI：
10.1007/s10853-018-03284-9
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发表时间：
--
影响因子：
4.5
通讯作者：
罗和安
中科院分区：
文献类型：
--
作者：
颜德健;刘冀锴;付星晨;刘平乐;罗和安
富硼半导体在无金属光催化剂家族中有着重要的贡献，近年来引起了人们的广泛关注。碳化硼（B4 C）属于典型的无金属富硼光催化剂，其在进一步优化中面临困难，主要是由于该材料的合成所需的极端条件。在目前的工作中，五种不同的过渡金属催化剂（铁，钴，镍，铜，和锌）进行了研究，以降低B4 C的结晶温度。Ni是最佳的催化剂，在850 °C下即可得到比表面积为130.55 m2 g-1的介孔B4 C粉末，比商业B4 C大27倍。通过光催化还原CO2和产生羟基自由基的实验，进一步评价了不同焙烧温度下Ni催化剂制备的B4 C的光催化性能。B4 C的结晶度和比表面积都会影响最终的光催化性能。对于B_4C光催化剂，我们首次发现结晶度对光生空穴的影响更为显著，而比表面积对光生电子的影响更为显著。在950 °C下制备的B4 C具有最好的光催化活性，其还原CO2和产生·OH自由基的活性分别是商业B4 C的3.1倍和2.1倍。本研究为低温合成B4 C晶体提供了重要的参考，并为无金属B4 C光催化剂在太阳能转化中的应用提供了新的契机。
Boron-rich semiconductors make significant contributions to the family of explored metal-free photocatalysts, which have attracted much attention in recent years. Boron carbide (B4C) belongs to a typical metal-free boron-rich photocatalyst which is facing difficulties in further optimization mainly due to the extreme conditions required for the synthesis of this material. In the present work, five different transition metal catalysts (Fe, Co, Ni, Cu, and Zn) were investigated for lowering the crystallization temperature of B4C. Ni is the best catalyst for the reaction and the crystalline mesoporous B4C powders can be obtained at merely 850 °C with a surface area of 130.55 m2 g-1, which is 27 times larger than commercial B4C. The photocatalytic properties of B4C prepared with Ni catalyst at different calcination temperatures were further evaluated by photocatalytic CO2 reduction and generation of hydroxyl radicals. Both the crystallinity and surface area of the B4C would influence the final photocatalytic properties. For B4C photocatalyts, we firstly found that the crystallinity would influence the photogenerated holes more significantly while the surface area would have more significant influence on the photogenerated electrons. The B4C obtained at 950 °C exhibits the best photocatalytic activities for both CO2 reduction and generation of •OH radicals, which are 3.1 and 2.1 times higher than the commercial B4C, respectively. This present study may provide crucial references for the low-temperature synthesis of crystalline B4C and new opportunities for the application of the metal-free B4C photocatalysts to solar energy conversion.