Ni2P纳米片用于光催化二氧化碳还原

Photocatalytic CO2 Reduction Using Ni2P Nanosheets

光催化还原二氧化碳是人工光合作用的重要组成部分,但由于还原二氧化碳的活化能过高导致其应用受到极大地限制。这里,我们报道Ni2P材料耦合光敏剂能够实现高效的光催化二氧化碳还原。此外,为了进一步的提高二氧化碳还原性能,一种合成超薄片层结构Ni2P纳米片的策略被采用,目的提高其对二氧化碳吸附能力和降低二氧化碳还原的活化能。一系列物理化学表征被实施,比如X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和原子力显微镜(AFM)等。这些实验结果证实了厚度为1.5 nm的超薄Ni2P纳米片被成功地制备。荧光实验结果揭示了Ni2P纳米片能够更高效地促进光生载流子的分离。此外,电化学实验证明了Ni2P纳米片具有较高的活性比表面积和电荷导电性,因此可以为二氧化碳转化提供更多的活性中心,从而加快其界面反应动力学。光催化二氧化碳还原实验结果展现了Ni2P纳米片光催化一氧化碳的生成速率为64.8μmol?h-1,且其活性是Ni2P颗粒光催化二氧化碳还原活性的四倍,同时它展现出较高化学稳定性。这项工作为超薄Ni2P纳米片在光催化二氧化碳中的应用提供了新的思路。

Artificial photosynthesis is an ideal method for solar-to-chemical energy conversion,wherein solar energy is stored in the form of chemical bonds of solar fuels.In particular,the photocatalytic reduction of CO2 has attracted considerable attention due to its dual benefits of fossil fuel production and CO2 pollution reduction.However,CO2 is a comparatively stable molecule and its photoreduction is thermodynamically and kinetically challenging.Thus,the photocatalytic efficiency of CO2 reduction is far below the level of industrial applications.Therefore,development of low-cost cocatalysts is crucial for significantly decreasing the activation energy of CO2 to achieving efficient photocatalytic CO2 reduction.Herein,we have reported the use of a Ni2P material that can serve as a robust cocatalyst by cooperating with a photosensitizer for the photoconversion of CO2.An effective strategy for engineering Ni2P in an ultrathin layered structure has been proposed to improve the CO2 adsorption capability and decrease the CO2 activation energy,resulting in efficient CO2 reduction.A series of physicochemical characterizations including X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM),and atomic force microscopy(AFM)were used to demonstrate the successful preparation of ultrathin Ni2P nanosheets.The XRD and XPS results confirm the successful synthesis of Ni2P from Ni(OH)2 by a low temperature phosphidation process.According to the TEM images,the prepared Ni2P nanosheets exhibit a 2D and near-transparent sheet-like structure,suggesting their ultrathin thickness.The AFM images further demonstrated this result and also showed that the height of the Ni2P nanosheets is ca 1.5 nm.The photoluminescence(PL)spectroscopy results revealed that the Ni2P material could efficiently promote the separation of the photogenerated electrons and holes in[Ru(bpy)3]Cl2?6H2O.More importantly,the Ni2P nanosheets could more efficiently promote the charge transfer and charge separation rate of[Ru(bpy)3]Cl2?6H2O compared with the Ni2P particles.In addition,the electrochemical experiments revealed that the Ni2P nanosheets,with their high active surface area and charge conductivity,can provide more active centers for CO2 conversion and accelerate the interfacial reaction dynamics.These results strongly suggest that the Ni2P nanosheets are a promising material for photocatalytic CO2 reduction,and can achieve a CO generation rate of 64.8μmol?h-1,which is 4.4 times higher than that of the Ni2P particles.In addition,the XRD and XPS measurements of the used Ni2P nanosheets after the six cycles of the photocatalytic CO2 reduction reaction demonstrated their high stability.Overall,this study offers a new function for the 2D transition-metal phosphide catalysts in photocatalytic CO2 reduction.