Supplementary Information. Origin of Chains of Au-PbS Nano-Dumbbells in. Space

Transcription

1 Supplementy Infomtion Oigin of Chins of Au-PbS Nno-Dumbbells in Spe Chndn Mondl, Ali Hossin Khn, Bidis Ds, Somobt Ahy* & Sujit Sengupt*, Cente fo Advned Mteils, Indin Assoition fo the Cultivtion of Siene, A & B Rj S.C. Mullik Rod, Jdvpu, Kolkt 000, Indi Tt Institute of Fundmentl Reseh, Cente fo Intedisipliny Sienes, Bundvn Colony, Nsingi, Hydebd 50005, Indi *Coesponding Authos E-mil: ms@is.es.in; sujit@tifh.es.in. These uthos ontibuted eqully to this wok

2 We hve ied out one expeiments on the self-ssembly of PbS nnoods. Diffeent onenttion dependnt TEM expeiments wee ied out, whee TEM gids wee peped fom diffeent onenttion of PbS nnood in toluene solutions. All the TEM obsevtion shows ggegted PbS nnoods nd no odeed ssembly in the fom of hins o y ws obseved in TEM Figue S - S. These ontol expeiments suggest the neessity of the Au tips fo the obseved odeing of dumbbells into hins nd ys. b Figue S. TEM imges of PbS nnoods t thee diffeent onenttions 0- moll-, b 4 0- moll-nd 8 0- moll- espetively. Figue S. A shemti of the lignd TOA moleule in the upight ondition. The geometi length of. nm is lulted ounting the length of the lkyl hins

3 geometilly. b A shemti of dumbbells within the hins long with the lignd TOA moleules dsobed on the sufe of the dumbbells. The ltel distne of.5 nm between the djent dumbbells is lge thn the length of two upight TOA moleules.4 nm suggesting tht the self-ssembly is not medited by the intedigittion of the TOA lkyl tils. Figue S. The seleted e eleton difftion SAED pttens fom Au-PbS ods showing pttens fom the fe-enteed ubi stutues of Au nd ubi ok slt stutue of PbS espetively. The SAED shows 00 PbS, 0 PbS nd PbS difftion ings with the inte-plne distnes of 0.9 nm, 0.0 nm nd 0. nm espetively of bulk ok slt PbS JCPDS The Au shows pominent Au nd 00 Au efletions JCPDS onfiming the HRTEM obsevtions.

4 0. nm b 0. nm 0.4 nm 0. nm 0.4 nm 0.9 nm 0.4 nm 0. nm 0.4 nm 0.4 nm Figue S4. The HRTEM imges of single dumbbells onsisting of nd 00 Au tips t the ends of 00 PbS ods, b, ltente oienttion of Au tips with Au nd 00Au fets long the hins of dumbbells. We hve ied out the sttistil nlysis on ou Au-tipped PbS dumbbells. Fo this pupose, we hve to quie shot fmed HRTEM imges fom the diffeent positions of TEM gid nd diffeent smples to pobe the ltente ystllogphi oienttions of the tips long the length of the hin of dumbbells. We hve monitoed fifty diffeent HRTEM imges fo sttistil nlysis; few of them e pesented in the Figue S5. Genelly, eh HRTEM imge fme ontins 4-5 dumbbells in ode to see the lttie finges of the Au tips nd PbS nnood. Within the sets of HRTEM imges pesented in the Figue S5, we hve monitoed dumbbells out of whih only one dumbbell shows stking fult with epet djent Au lttie plnes t the tips. We hve monitoed 00 of suh dumbbells fo sttistil nlysis in whole. We found tht ~% of the 4

5 dumbbells do not mintin ltente oienttions of 00 Au nd Au plnes with in the ssembled hins. Figue S5. HRTEM imges of Au tips t the ends of Au-PbS dumbbells -d showing ltente oienttion of Au nd 00 Au fets long the hins of dumbbells. 5

6 Summy of DFT lultions The intetion between diffeent fets of PbS nnoods nd Au tips e estimted using DFT studies pefomed on tomi lustes epesenting diffeent fets of Au tip nd PbS nnood. PbS nnood is modelled using two lyes of PbS lttie mimiking 00 PbS fets, whih e pobble sites fo Au deposition. Diffeent fets of Au lustes toms in two lyes e nged s Au, 0 Au nd 00 Au fo intetion with 00 PbS nnoods. Diffeent fets of PbS nd Au lustes e gdully bought lose in steps fom lge distne nd the hnges in totl enegies e lulted. The eletoni stutue studies e done using Density Funtionl Theoy DFT s implemented in Gussin 0 softwe M. J. Fish, Gussin0, Revision C.0, Gussin In.: Wllingfod, CT, 004. The hybid funtionl BLYP is used long with -G** bsis set fo S toms nd LnlDZ bsis set with effetive oe potentil is used fo Au nd Pb toms. To vlidte the esults, we hve lso used PBEPBE funtionl see the Tble below. Tble S. Intetion enegies in kev lulted using diffeent DFT funtionls.

7 Dipole moment lultion of PbS nnood Figue S. Shemti fo model PbS nnood nd the top view of the lye t the end of the nnood. The od onsists of 4 of suh lyes. The distne between two lyes is, whih is equl to hlf the lttie pmete of PbS. Thus, the length of the od beomes ~ nm long z-dietion, nd long x nd y-dietions it's dimension is ~.8 nm espetively. Chge of eh Pb tom yellow sphees is e nd tht of eh S tom gey sphee is - e, whee e is hge of n eleton. A ptiul lye in x-y plne n be eithe Pb-ih with 5 Pb toms nd 4 S toms o S-ih with 5 S toms nd 4 Pb toms. The od onsists of 4 of suh lyes. The top nd bottom lye is onstuted to be S-ih due to tthment of Au on PbS nnood. Then thee e S-ih lyes nd 0 Pb-ih lyes.

8 In S-ih lye net hge-e nd in Pb-ih lye net hgee. So, the net hge of the nnood with one ext S-ih lye beomes -e. To neutlize it, two Pb toms e ssumed to be in Pb stte insted of Pb stte. Sine both of these hges e ve, they ty to eside pt fom eh othe. Hene we onside one of them to be situted t the top most lye nd the othe t the bottom most lye. The ight figue shows the topmost lye o the lye t the bottom whee the onge sphee indites the position of the Pb ion. To lulte the dipole moment, we hve onsideed the oigin t the ente of mss of the od. The dipole moment of n ssembly of N numbe of hges is defined s: Hee, fo Pb is e nd fo S is -e, whee e is the hge of one eleton. Hene, whee, ipb is the position of i th Pb tom nd is is the position of i th S tom. With the bove geometil lultions, the z-omponent of net dipole moment n be desibed s follows: The x nd y omponent of net dipole moment i.e x nd y fo eh lye is individully zeo due to symmety exept fo those two lyes onsisting of Pb ions. One suh lye 8

9 is shown in the ight pnel of the bove Figue S. x fo the lye n be 0.0, e-e, e-e, e-e depending on whethe Pb emin on the lines x0, x-x, x-x, x-x espetively. The sme is vlid fo y. Fo two suh lyes, mximum possible vlue of x o y ould be e whih is ~85 Debye. Hene, eh PbS nnood my possess stong dipole moment even in the ubi ystllogphi phse. Now, the dipole-dipole intetion enegy between two dipoles nd septed by distne is given by, Whee is the pemittivity of toluene the solution. whee, nd 0 being the eltive pemittivity nd the pemittivity of fee spe espetively. Fo toluene, ~.8. The intetion enegy between two PbS nnoods with dipole moment of the ode of ~80 Debye nd septed by distne 5 nm in solution phse is lulted to be 0-0 Joule whih is equl to ~k B T t oom tempetue. Moleul Dynmis simultion The intetion potentil between Au tips The intetion between two type- ptiles, is Hmke intetion between two lge sized olloidl ptiles s given below: 9

10 0, ln A A,,,,,, 0,, 800 R A R A <. Whee, A, is the Hmke onstnt nd nd e the dii of the two olloidl ptiles, nd is the utoff. In ou se.0. The intetion between type- ptile nd type-/type- ptile is given by:, /, /, /, / 4 4, /, /, / 0,, A <.. The intetion between two type- ptiles is given below:,,,,,,, 0,, A <...

11 nd two type- ptiles o type- ptile nd type- ptile intets with simple Lennd-JonesLJ intetion: m, n m, n 4Am, n 0, m, n m, n m, n, < m, n..4 Whee, m, n, exept m n. Ou model epesents the min fetues of the luste-luste intetions without the omplexity of n ll-tom ppoh. The fitted vlues of the pmetes e tbulted below. A,.0 A, 40.0 A, 0. A, 0.0 A,.0 A,.0,.0, 0.989,.09,.00,.05,.4,.0, 4.0, 4.0,.0,.0, 4.0 Tble S. Pmetes in the intetion potentil. All quntities e expessed in edued units.

12 Figue S. Phse-digm of D system of dumbbells in -T plne obtined fom MD simultions. The ed dots nd the blk line onneting these iles show the phse boundy of the honeyomb solid phse. The blk ow shows the lowe limit of the honeyomb solid obtined fom elsti onstnt lultions t T0. Blk dshed lines show expeted phse boundies of gsliquid GL, liquidtingul solid LTS, honeyomb solid HStingul solid nd honeyomb solidliquid phses. The system hs liquid phse whih exists t highe density thn the honeyomb solid phse beuse of the pthy intetion. The two phse oexistene egions e shded in gey. A,.0 A, 0.0 A, 8.55 A,.0 A,.0 A, 4.9,.0,.9, 5.48,.0,.0, 4., 0.0, 8.0, 8.05,.5, 5.0, 8.0 Tble S. Pmetes used to lulte the phse-digm shown in Figue S. All quntities e expessed in edued units.