Nanoparticles immersed in liquids (i.e. water or electrolyte solutions) change their solid-gas interface into a solid-liquid interface which substantially modifies the surface chemistry of the particles. Consequently, existing excess surface charges lead to an electrochemical double layer formation around the dispersed nanoparticles. Furthermore, the structure of the electrochemical double layer has a profound influence on reaction kinetics . Many properties and applications of nanoparticles such as ion exchange, adsorption or catalytic reactions rely on the structure of the solid-liquid interface. The solid-liquid interface plays a major role in photocatalytic water splitting, electrocatalysis, solid-electrolyte batteries and fuel cells. SnO2 is a material that finds application as photocatalyst or in lithium ion batteries as anode material.
Here, chemical vapor synthesized (CVS) SnO2 nanocrystals are studied with X-ray absorption spectroscopy (XAS) in liquid colloids. The local structural environment of tin dioxide – water interface is analyzed over a range pH values (using HBr and RbOH) and the ionic strength (RbBr) to reveal changes in the interfacial region due to the modified the particle-ion interaction at the particle surface. XAS spectra at the Sn K-edge, Br K-edge and Rb K-edge are measured and compared to dry SnO2 nanocrystals.
 P. Mulvaney, V. Swayambunathan, F. Grieser, D. Meisel, Effect of zeta potential on electron transfer to colloidal iron oxides, Langmuir, 6 (1990) 555-559.
Advanced Photon Source (APS) at Argonne National Laboratory for providing beamtime
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E