A comprehensive review on catalysts for seawater electrolysis

Seawater electrolysis is a sustainable energy conversion technology that generates clean energy by splitting seawater into hydrogen and oxygen.However,the catalysts used in seawater electrolysis often face significant stability challenges because of the high concentration of salt ions and other impurities present in seawater.This review aims to discern the pivotal factors influencing catalyst stability in seawater electrolysis,elucidate the corrosion and electrochemical degradation mechanisms,and delve into the various strategies employed to enhance catalyst stability.These strategies encompass catalyst material selection,surface modification techniques,catalyst support materials,and catalyst design strategies.By gaining deeper insights into the obstacles and innovations concerning catalyst stability in seawater electrolysis,this review strives to expedite progress toward the commercialization and widespread adoption of this technology as a renewable and feasible approach for hydrogen production.Ultimately,the goal is to foster a cleaner and more sustainable future by enabling the efficient and enduring generation of hydrogen from seawater.

Surface chemistry considerations of gangue dissolved species in the bastnaesite flotation system

Inefficient flotation of bastnaesite remains a challenge in the production of rare earth elements.This study aimed to investigate the dissolution and adsorption behaviour of species that are commonly released into bastnaesite flotation pulp from Ca/Ba-bearing gangue minerals.The influence and corresponding mechanisms on the bastnaesite mineral surface and collectors,namely sodium oleate(NaOL),were evaluated experimentally based on micro-flotation,zeta potentials,in situ attenuated total reflection Fourier transform infrared spectroscopy(ATRFTIR),and X-Ray photoelectron spectroscopy(XPS)analyses.The flotation recovery of bastnaesite significantly decreased from ~95% to ~25%,~15%,~80%,~25% when exposed to calcite,fluorite,barite,and mixed dissolved species,respectively.The zeta potential of bastnaesite was pH sensitive,indicating that H^(+) and OH^(−)determine the surface potential of bastnaesite.Solution chemistry analyses revealed that the presence of the dissolved species differed at various pH values.In situ ATR-FTIR demonstrated the different effects of the dissolved species from calcite,fluorite,and barite on collector adsorption.The former two dissolved species mainly depressed the chemisorption of the NaOL monomers(RCOO^(-)),whereas calcite also affected the physical adsorption of the oleic acid molecular dimer(RCOOH·RCOO^(-)).Moreover,the barite dissolved species only affected the physical adsorption of the NaOL species.The results of XPS analysis revealed that dissolved species from these three gangues could pre-adsorbed onto bastnaesite and affected the interaction with the collector.Density functional theory calculations were employed to provide further theoretical insights into the interactions between the dissolved species from calcite,fluorite,and barite and NaOL.