On the surface chemistry of silicon under reducing conditions: An SRPES investigation

Silicon electrodes were conditioned in alkaline solution at potentials negative from open circuit (ocp). The dark I-V characteristic of n-Si(1 1 1) in accumulation reveals Butler-Volmer behaviour for outer sphere charge transfer of the hydrogen evolution reaction. Deconvoluted synchrotron radiation photoelectron spectroscopy (SRPES) data are used to identify reaction intermediates of the chemical and electrochemical pathways and are compared to existing models on a molecular base. The results indicate the existence of postulated negatively charged surface species. Comparison of density functional theory (DFT) calculations and core level binding energy shifts of the Si 2p3/2, the 2p1/2 line and the O 1s line allows the assignment of twofold coordinated surface reaction intermediates.