This work shows the potential of nickel (Ni) nanoparticles (NPs) stabilized by polymers for accelerating carbon dioxide (CO2) dissolution into saline aquifers. The catalytic characteristics of Ni NPs were investigated by monitoring changes in diameter of CO2 microbubbles. An increase in ionic strength considerably reduces an electrostatic repulsive force in pristine Ni NPs, thereby decreasing their catalytic potential. This study shows how cationic dextran (DEX), nonionic poly(vinyl pyrrolidone) (PVP), and anionic carboxy methylcellulose (CMC) polymers, the dispersive behaviors of Ni NPs can be used to overcome the negative impact of salinity on CO2 dissolution. The cationic polymer, DEX was less adsorbed onto NPs surfaces, thereby limiting the Ni NPs’ catalytic activity. This behavior is due to a competition for Ni NPs’ surface sites between the cation and DEX under high salinity. On the other hand, the non/anionic polymers, PVP and CMC could be relatively easily adsorbed onto anchoring sites of Ni NPs by the monovalent cation, Na+. Considerable dispersion of Ni NPs by an optimal concentration of the anionic polymers improved their catalytic capabilities even under unfavorable conditions for CO2 dissolution. This study has implications for enhancing geologic sequestration into deep saline aquifers for the purposes of mitigating atmospheric CO2 levels.

Li-O2 and Na-O2 batteries offer the promise of increased energy densities compared to Li-ion batteries but suffer from poor power and cycle life. Despite considerable research on the oxygen reduction reaction (ORR) in these cells at room temperature, limited work has been performed to understand the influence of temperature on the discharge characteristics. In this Letter, we show that the discharge capacity of Li-O2 cells increases with increasing temperature while the discharge capacity of Na-O2 cells decreases over the same temperature range. We show that the discharge behavior of Na-O2 cells is dominated by increasing superoxide solubility with decreasing temperature. On the other hand, increasing Li+-O2 – coupling strength with decreasing temperature promotes the formation of insoluble Li2O2 through either disproportionation or a 2e– reduction mechanism, leading to reduced discharge capacity in Li-O2 cells. Such findings highlight the complex and important effect that temperature has on ORR in Li-O2 and Na-O2 batteries.