First-principles investigation of β-Ge3N4 loaded with RuO2 cocatalyst for photocatalytic overall water splitting  

作　　者：Yanxia Ma Miaomiao Wang Xin Zhou 

机构地区：[1]College of Environment and Chemical Engineering,Dalian University,Dalian 116622,Liaoning,China

出　　处：《Journal of Energy Chemistry》2020年第5期24-32,共9页能源化学（英文版）

基　　金：the National Natural Science Foundation of China under Grant 21473183;the open fund of Key Laboratory of Computational Physical Sciences(Fudan University),Ministry of Education.

摘　　要：β-Ge3N4 loaded with nanoparticulate RuO2 as a cocatalyst is the first successful non-oxide photocatalyst for overall water splitting.To get an insight into the working mechanism of this particular photocatalytic system,we have calculated geometrical structures of low-index surfaces forβ-Ge3N4.Analysis of surface energies indicates that the most preferentially exposed surface is(100).The band gap of surface is narrower than that of bulk due to the dangling bonds.Dissociative water adsorption on(100)surface is thermodynamically favorable.The adsorption behavior of(RuO2)n(n=2,3,and 4)clusters on theβ-Ge3N4(100)surface has been explored.It is found that all the clusters bind to(100)surface strongly by forming interfacial bonds so that the adsorptions are exothermic processes.The calculation on density of states forβ-Ge3N4(100)surface loaded with(RuO2)nclusters reveals that photo-induced electrons tend to accumulate on(RuO2)nclusters and holes tend to stay inβ-Ge3N4.Based on the theoretical indication of Type-II staggered band alignment,we have proposed that in photocatalytic water splitting reaction,oxygen evolution reaction is inclined to occur on the surface ofβ-Ge3N4 while hydrogen evolution reaction is apt to occur on(RuO2)nclusters.In a word,loading RuO2 nanoparticles as a reduction cocatalyst benefits the charge separation inβ-Ge3N4.Furthermore,attaching(RuO2)nclusters ontoβ-Ge3N4(100)surface results in the redshift of absorption edge and the increase of absorption intensity.Our calculations have reasonably explained the experimental observation on the decomposition of water into H2 and O2 after loading RuO2 cocatalyst inβ-Ge3N4 photocatalyst.β-Ge3N4 loaded with nanoparticulate RuO2 as a cocatalyst is the first successful non-oxide photocatalyst for overall water splitting. To get an insight into the working mechanism of this particular photocatalytic system, we have calculated geometrical structures of low-index surfaces for β-Ge3N4. Analysis of surface energies indicates that the most preferentially exposed surface is（100）. The band gap of surface is narrower than that of bulk due to the dangling bonds. Dissociative water adsorption on（100） surface is thermodynamically favorable. The adsorption behavior of（RuO2）n（n = 2, 3, and 4） clusters on the β-Ge3N4（100） surface has been explored. It is found that all the clusters bind to（100） surface strongly by forming interfacial bonds so that the adsorptions are exothermic processes. The calculation on density of states for β-Ge3N4（100） surface loaded with（RuO2）nclusters reveals that photo-induced electrons tend to accumulate on（RuO2）nclusters and holes tend to stay in β-Ge3N4. Based on the theoretical indication of Type-II staggered band alignment, we have proposed that in photocatalytic water splitting reaction,oxygen evolution reaction is inclined to occur on the surface of β-Ge3N4 while hydrogen evolution reaction is apt to occur on（RuO2）nclusters. In a word, loading RuO2 nanoparticles as a reduction cocatalyst benefits the charge separation in β-Ge3N4. Furthermore, attaching（RuO2）nclusters onto β-Ge3N4（100）surface results in the redshift of absorption edge and the increase of absorption intensity. Our calculations have reasonably explained the experimental observation on the decomposition of water into H2 and O2 after loading RuO2 cocatalyst in β-Ge3N4 photocatalyst.

关 键 词：β-Ge3N4 RUO2 COCATALYST PHOTOCATALYTIC water splitting Density functional theory 

分 类 号：TQ116.2[化学工程—无机化工] O643.3[理学—物理化学] O644.1[理学—化学]