具有直接Z型光催化机制的非金属BC4N/aza-CMP异质双层的光催化固氮性能  

Direct Z-scheme photocatalytic nitrogen reduction to ammonia with water in metal-free BC4N/aza-CMP heterobilayer

作　　者：范英才 张志华 王娟 马西奎 赵明文 Yingcai Fan;Zhihua Zhang;Juan Wang;Xikui Ma;Mingwen Zhao(School of Information and Electronic Engineering,Shandong Technology and Business University,Yantai 264005,China;School of Physics and State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China)

机构地区：[1]School of Information and Electronic Engineering,Shandong Technology and Business University,Yantai 264005,China [2]School of Physics and State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China

出　　处：《Science China Materials》2023年第11期4377-4386,共10页中国科学(材料科学(英文版)

基　　金：supported by the National Natural Science Foundation of China(21833004);Taishan Scholar Program of Shandong Province;the Natural Science Foundation of Shandong Province(ZR2020QA055)。

摘　　要：我们设计了一种不含金属的二维双层异质结构BC_(4)N/aza-CMP,该体系可在水溶液中将N2分子通过光催化作用还原为氨.通过密度泛函理论和非绝热分子动力学方法,我们发现该异质结构中的光生载流子遵循直接Z型迁移机制.这将有效分离光生电荷并使氮还原反应和氧发生反应分别在BC_(4)N层和aza-CMP层上进行,实现反应位点的空间分离.值得一提的是,BC_(4)N上的B原子可以有效吸附N2分子并激活N≡N键,这将降低氮还原反应的过电势并促进随后的质子化进程,且该异质双层具有适宜的带隙和带边位置,能够有效吸收太阳光并提供充足的驱动力来触发氧化还原反应,实现无任何牺牲剂辅助的光催化氨合成.本工作将为直接Z型固氮光催化剂的设计提供重要借鉴,并促进太阳能驱动的氨合成的发展.Photocatalytic ammonia(NH_(3))synthesis from air and water without external energy input or sacrificial agents is an attractive approach for nitrogen fixation.How-ever,finding a suitable photocatalyst with strong optical ab-sorption,efficient photogenerated carrier separation,and adequate driving force(potentials of photoinduced carriers)to trigger the nitrogen reduction reactions(NRRs)and oxygen evolution reactions(OERs)simultaneously is challenging.Herein,we propose a direct Z-scheme photocatalytic system based on a two-dimensional metal-free BC_(4)N/aza-CMP het-erobilayer.The results of density functional theory and time-dependent ab initio nonadiabatic molecular dynamics reveal that the photoexcited carriers in the BC_(4)N/aza-CMP hetero-bilayer follow a Z-scheme migration route,leading to the ef-ficient charge carrier separation and spatially separated reaction sites for NRR(BC_(4)N layer)and OER(aza-CMP layer).Moreover,the appropriate band gaps and energy levels of the BC_(4)N/aza-CMP heterobilayer enable efficient solar energy capture and provide sufficient driving force(1.01 V for NRR and 2.11 V for OER)to initiate the redox reactions.Ad-ditionally,the activation of the N≡N bond by B atoms in the BC_(4)N layer promotes the sequential hydrogenation of N atoms and reduces the overpotential of NRR.Consequently,the NRR and OER can proceed spontaneously,driven by photo-generated carriers with no need for sacrificial agents.The predicted maximum value of solar-to-chemical efficiency is 7.59%.This work will be an important reference for the ra-tional design of direct Z-scheme photocatalysts for NRR and promote the development of solar-driven NH_(3) synthesis.

关 键 词：photocatalytic NH3 synthesis direct Z-scheme pho-tocatalyst energy conversion efficiency nonadiabatic molecular dynamics calculations 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学]