Critical review on the synthesis, characterization, and application of highly efficient metal chalcogenide catalysts for fuel cells

• Metal chalcogenides can perform selective catalysis for ORR, and low poisoning catalysis for fuel oxidation. • 3 electrodes system examines catalysts’ activity for ORR or fuel oxidation, and in-situ tests mimic the cell's real time operation. • Various synthesis routes can tailor metal chalcogenides to fit desirable dimensions, sizes, stoichiometries, and morphologies. The shift in the energy sector toward green resources makes fuel cells increasingly relevant as a supplier of green and sustainable energy. However, factors such as expensive catalysts, anodic poisoning, and fuel crossover reduce the lifetime and performance of the fuel cells, necessitating catalysis improvement. This review article presents the unique capabilities of metal chalcogenides (MC) as tailored catalysts, elucidating their synthesis, testing techniques, and performance evaluations. MC catalysts are matured via various physical and chemical methods to control their morphology, quantity, dimension, and size. Upon synthesis, the catalyst performance is quantified using three-electrode cells, followed by tests in fuel-cell prototypes. As anodic catalysts, MCs oxidize various fuels such as methanol, ethanol, urea, and impure H 2 at high current densities and low onset potentials, while hindering the poisoning species. As cathodic catalysts, MCs exhibit current values similar to that exhibited by their noble metal counterparts while reducing oxygen selectively in the vicinity of the fuels via four electron transfers at a wide range of potentials.