Anionic formulation of electrolyte additive towards stable electrocatalytic oxygen evolution in seawater splitting

Hydrogen generation through seawater electrolysis provides a promising,attractive pathway towards the utilization of sustainable energy.However,the catalytic activity and stability of oxygen evolution anode are severely limited by the chloride-induced corrosion and competitive oxidation reactions.In this work,we demonstrate an anion-assisted performance improvement strategy by quick and universal screening of electrolyte additive via correlating Cl-repellency with the anionic properties.Particularly,the addition of phosphate ions is found to enable highly stable alkaline seawater splitting at industry-level current density(0.5 A cm^(-2))over 500 h using transition metal hydroxides as anodic electrocatalysts.In situ experiments and theoretical simulations further reveal that the dynamic anti-corrosion behaviors of surface-adsorbed phosphate ions are attributed to three factors including repelling Cl-ions without significantly blocking OH-diffusion,preventing transition metal dissolution and acting as a local pH buffer to compensate the fast OH-consumption under high current electrolysis.

Amorphous NiO_(n)coupled with trace PtO_(x)toward superior electrocatalytic overall water splitting in alkaline seawater media

Developing corrosion resistance bifunctional electrocatalysts with high activity and stability toward both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),especially electrolysis in seawater,is of prime significance but still pressingly challenging.Herein,in-situ introduced PtO_(x)on the derivative amorphous NiO_(n)is prepared via heat treatment of Ni ZIFL nanosheets on nickel foam under low temperature(PtO_(x)-NiO_(n)/NF).The synthesized PtO_(x)-NiO_(n)/NF possesses suprahydrophilic and aerophilic surface,then in favor of intimate contact between the electrode and electrolyte and release of the generated gas bubbles during the electrocatalysis.As a result,the in-situ PtO_(x)-NiO_(n)/NF electrode presents outstanding bifunctional activity,which only requires extremely low overpotentials of 32 and 240 mV to reach a current density of 10 mA·cm^(-2)for HER and OER,respectively,which exceeds most of the electrocatalysts previously developed and even suppresses commercial Pt/C and RuO_(2)electrodes.As for two-electrode cell organized by PtO_(x)-NiO_(n)/NF,the voltages down to 1.57 and 1.58 V are necessary to drive 10 mA·cm^(-2)with remarkable durability in 1 M KOH and alkaline seawater,respectively,along with remarkable stability.Moreover,a low cell voltage of 1.88 V is needed to achieve 1,000 mA·cm^(-2)toward water-splitting under industrial conditions.This study provides a new idea for designing in-situ amorphous metal oxide bifunctional electrocatalyst with strong Pt–support interaction for overall water splitting.