Jun Li

Capacitive deionization (CDI) is a promising technology for purifying brackish water into drinking fresh water based on reversible electrosorption of ions into the electrical double layer (EDL). Here, we demonstrate a facile approach to immobilizing charges on activated carbon (AC) electrodes made of a safe, highly hydrophilic binder via spontaneous adsorption of ionic surfactants. The amount of surfactant adsorption is carefully quantified and the pore structure is characterized with Brunauer‐Emmett‐Teller surface analysis. Electrochemical characterization shows that a large portion of the AC surface is accessible by ions in the aqueous solution, facilitating ion adsorption in CDI processes. The immobilized ionic surfactants regulate the counterions and co‐ions in the EDL, behaving like ion‐exchange membranes. The stability, charge efficiency, and energy consumption during CDI are substantially improved compared to bare AC films. Importantly, it enables an “inverted CDI mode” with ion adsorption at the open‐circuit condition to neutralize the immobilized charges on the electrode surface and ion desorption by an inverted voltage bias. After optimization, a high average salt adsorption capacity of 14.6 mg _NaCl /g _{AC film} was obtained with surfactant‐immobilized asymmetric cells in constant current mode for 50 cycles. These results provide new insights toward developing future CDI technologies for water purification.

The availability of durable, high‐performance electrocatalysts for the hydrogen oxidation reaction (HOR) is currently a constraint for anion‐exchange membrane fuel cells (AEMFCs). Herein, a rapid microwave‐assisted synthesis method is used to develop a core–shell catalyst support based on a hydrogenated TiO₂/carbon for PtRu nanoparticles (NPs). The hydrogenated TiO₂ provides a strong metal‐support interaction with the PtRu NPs, which improves the catalyst's oxophilicity and HOR activity compared to commercial PtRu/C and enables greater size control of the catalyst NPs. The as‐synthesized PtRu/TiO₂/C‐400 electrocatalyst exhibits respectable performance in an AEMFC operated at 80 °C, yielding the highest current density (up to 3× higher) within the catalytic region (compared at 0.80–0.90 V) and voltage efficiency (68%@ 0.5 A cm⁻²) values in the compared literature. In addition, the cell demonstrates promising short‐term voltage stability with a minor voltage decay of 1.5 mV h⁻¹. This “first‐of‐its‐kind in alkaline” work may open further research avenues to develop rapid synthesis methods to prepare advanced core–shell metal‐oxide/carbon supports for electrocatalysts for use in the next‐generation of AEMFCs with potential applicability to the broader electrochemical systems research community.