PNNL

Abstract

Prediction of the interactions between H2S-contaminated hydrogen fuel and Ni surfaces under conditions similar to those for solid oxide fuel cell (SOFC) operation using DFT (density function theory) calculations (with thermodynamic corrections) has resulted in a new S–Ni phase diagram, which suggests the existence of an intermediate state between clean Ni surfaces and nickel sulfides – sulfur atoms adsorbed on Ni surfaces. This prediction is consistent with many experimental observations relevant to sulfur poisoning of Nibased anodes in SOFCs, which cannot be explained using the existing S–Ni bulk phase diagram from classical thermodynamics. The accurate prediction of the adsorption phase is vital to a fundamental understanding of the sulfur poisoning mechanism of Ni-based anodes under SOFC operating conditions.