稀土掺杂对半导体光催化剂性能影响的进展(特邀)

Research Progress on Effect of Rare Earth Doping on Performance of Semiconductor Photocatalysts(Invited)

光催化是能够利用太阳能进行能源转化和环境治理的环保方法。稀土元素在光催化中具有独特的电荷调控机制和光学改性机制,能够有效提升传统半导体的光催化活性。首先,从提升半导体光催化剂光电性能和降低载流子复合率方面,介绍了稀土元素的掺杂对半导体光催化剂性能的调控,并根据稀土元素的分类和掺杂所占组元数的不同,分别从一元稀土掺杂、二元共掺杂到多元及高熵稀土掺杂的角度综述了稀土改性半导体光催化剂的研究进展和相应的光催化动力学机理。通过总结可知,稀土元素较大的原子半径能够有效地引起半导体光催化剂的晶格畸变从而增加半导体的缺陷,达到细化颗粒度,暴露催化剂活性位点的作用;同时,稀土元素特殊的能带结构能有效调整半导体光催化剂的光电性能,促进载流子的高效分离并拓宽其可见光的响应范围,促进光催化反应高效进行。最后,阐述和总结了稀土元素改性对于半导体光催化剂活性改善的重要意义并进行了展望。

Photocatalysis is an environmental protection method that can utilize solar energy for energy conversion and environmental governance.Among them,catalysts play a crucial role as an important part of photocatalysis.At present,the most commonly used catalysts are still traditional semiconductor catalysts,which have good environmental adaptability and stability,the large specific surface area and excellent photocatalytic intrinsic activity to ensure their excellent catalytic activity.Meanwhile,semiconductor photocatalysts have lower production costs and abundant reserves of raw materials on Earth,which also ensures their larger production volume and lower production costs.However,the bandgap of semiconductor catalysts is generally wide,which leads to high carrier recombination rate and insufficient visible light response,thereby limiting the efficient photocatalytic reaction.Rare earth elements,as dopants,have unique charge control mechanisms and optical modification mechanisms in photocatalysis,which can effectively enhance the photocatalytic activity of traditional semiconductors.Rare earth elements are a collective term for a total of 17 elements,including 15 lanthanide elements and scandium(Sc)and yttrium(Y),which have similar chemical properties to lanthanide elements.China is a major country in rare earth resources,with reserves of around 44 million tons,accounting for approximately 34%of the global rare earth reserves and ranking first in the world.Nowadays,rare earth elements have been widely used in metallurgy,chemical industry,aerospace transportation,and military fields,demonstrating their significant application value.They also have profound research significance in the field of photocatalysis industry,such as photocatalytic degradation of industrial printing and dyeing wastewater,reduction of CO2,preparation of hydrogen and oxygen from photocatalytic water splitting,etc.This article mainly introduces the regulation of rare earth element doping on the performance of semiconductor photocatalysts from the aspects of improving the photoelectric performance of semiconductor photocatalysts and reducing the recombination rate of charge carriers.Based on the classification of rare earth elements and the different number of doping components,the research progress and corresponding photocatalytic kinetic mechanisms of rare earth modified semiconductor photocatalysts are reviewed from the perspectives of single element rare earth doping,co doping of two rare earth elements,and multi element and high entropy rare earth doping.Through summary,it can be concluded that the larger atomic radius of rare earth elements can effectively cause lattice distortion of semiconductor photocatalysts,thereby increasing semiconductor defects,achieving the effect of refining particle size and exposing catalyst active sites;meanwhile,the unique band structure of rare earth elements can effectively adjust the photoelectric performance of semiconductor photocatalysts,promote efficient separation of charge carriers,and broaden their corresponding range of visible light.In addition,the up-conversion effect of some rare earth elements can also greatly improve the utilization of sunlight,compensate for the weak visible light absorption of semiconductor catalysts,and then promote the efficient progress of photocatalytic reactions.There are also studies indicating that doping with binary or more rare earth elements can also produce synergistic effects,jointly promoting the progress of specific photocatalytic reactions,such as the adsorption of reaction intermediates in photocatalytic reduction of CO_(2).In addition,when the doping type of rare earth elements reaches a high entropy level of five or more,it not only has excellent visible light response ability and large specific surface area,but also has stability and high entropy effect similar to high entropy alloys.These new advantages effectively enhance its photocatalytic activity and also saves a lot of consumption.Rare earth elements,as emerging dopants,have unique photocatalytic advantages.At the end of this article,the importance of rare earth element modification in improving the activity of semiconductor photocatalysts is elaborated and summarized,and corresponding prospects are made.