Search

The electrochemical desalination technique is recognized as a promising solution to alleviate freshwater shortages, challenges yet persists in achieving optimal energy efficiency and cost‐effectiveness. Herein, a hybrid acid/alkali zinc air desalination battery (hAA‐ZADB) capable of concurrent desalination and high‐power density is reported. To improve cathodic efficiency and cost‐effectiveness, an electrocatalyst with dual atomic Fe–Mn sites on porous dodecahedral carbon (Mn‐Fe/p‐DC) is fabricated through a simple direct pyrolysis strategy for oxygen reduction reaction (ORR). The Mn–Fe/p‐DC‐900 electrocatalyst demonstrates exceptional electrocatalytic activity (E1/2 = 0.8 V in 0.5 m H2SO4) for ORR. This innovative hybrid acid/alkali cell design, coupled with advanced electrocatalysts, empowers the hAA‐ZADB system to achieve outstanding performance benchmarks with a high open circuit voltage of 2.22 V, an impressive power density of 375 mW cm−2, and notably elevated energy output of 106.9 kJ mol−1 even at a current density of 100 mA cm−2 during desalination. Distinguishing this work is its additional functionality, evident in a rapid salt removal rate of 3.64 mg cm−2 min−1 during desalination, achieving an impressive 88.67% removal of 0.6 M NaCl. This study highlights the promising potential of employing metallic air batteries for a self‐powered desalination technique applicable to specific scenarios. [ABSTRACT FROM AUTHOR]

Transition metal single atoms anchored on nitrogen‐doped carbon (M‐N‐C) matrix with M‐N‐C active sites have shown to be promising catalysts for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Herein, a hybrid catalyst with low‐level loading of atomic Pt and Co species encapsulated in nitrogen‐doped graphene (Pt@CoN4‐G) is developed. The Pt@CoN4‐G shows low overpotential for HER in wide‐pH electrolyte and manifests improved mass activity with almost eight times greater than that of Pt/C at an overpotential of 50 mV. The Pt@CoN4‐G also exhibits a top‐level ORR activity (half‐wave potential, E1/2 = 0.893 V) and robust stability (>200 h) in alkaline medium. Using theoretical calculations and comprehensive characterizations , the strong metal–support interactions between Pt species and CoN4‐G support and synergistical cooperation of multiple active sites are clarified. A flow alkali‐Al/acid hybrid fuel cell using Pt@CoN4‐G as cathode catalyst delivers a large power density of 222 mW cm−2 with excellent stability to achieve simultaneously hydrogen evolution and electricity generation. In addition, Pt@CoN4‐G endows a flow Zn‐air battery with high power density (316 mW cm−2), good stability under large current density (>100 h at 100 mA cm−2), and long cycle life (over 600 h at 5 mA cm−2). [ABSTRACT FROM AUTHOR]

Electrosynthesis of H2O2 has great potential for directly converting O2 into disinfectant, yet it is still a big challenge to develop effective electrocatalysts for medical‐level H2O2 production. Herein, we report the design and fabrication of electrocatalysts with biomimetic active centers, consisting of single atomic iron asymmetrically coordinated with both nitrogen and sulfur, dispersed on hierarchically porous carbon (FeSA‐NS/C). The newly‐developed FeSA‐NS/C catalyst exhibited a high catalytic activity and selectivity for oxygen reduction to produce H2O2 at a high current of 100 mA cm−2 with a record high H2O2 selectivity of 90 %. An accumulated H2O2 concentration of 5.8 wt.% is obtained for the electrocatalysis process, which is sufficient for medical disinfection. Combined theoretical calculations and experimental characterizations verified the rationally‐designed catalytic active center with the atomic Fe site stabilized by three‐coordinated nitrogen atoms and one‐sulfur atom (Fe‐N3S‐C). It was further found that the replacement of one N atom with S atom in the classical Fe‐N4‐C active center could induce an asymmetric charge distribution over N atoms surrounding the Fe reactive center to accelerate proton spillover for a rapid formation of the OOH* intermediate, thus speeding up the whole reaction kinetics of oxygen reduction for H2O2 electrosynthesis. [ABSTRACT FROM AUTHOR]

The development of precious‐metal alternative electrocatalysts for oxygen reduction reaction (ORR) is highly desired for a variety of fuel cells, and single atom catalysts (SACs) have been envisaged to be the promising choice. However, there remains challenges in the synthesis of high metal loading SACs (>5 wt.%), thus limiting their electrocatalytic performance. Herein, a facile self‐sacrificing template strategy is developed for fabricating Co single atoms along with Co atomic clusters co‐anchored on porous‐rich nitrogen‐doped graphene (Co SAs/AC@NG), which is implemented by the pyrolysis of dicyandiamide with the formation of layered g‐C3N4 as sacrificed templates, providing rich anchoring sites to achieve high Co loading up to 14.0 wt.% in Co SAs/AC@NG. Experiments combined with density functional theory calculations reveal that the co‐existence of Co single atoms and clusters with underlying nitrogen doped carbon in the optimized Co40SAs/AC@NG synergistically contributes to the enhanced electrocatalysis for ORR, which outperforms the state‐of‐the‐art Pt/C catalysts with presenting a high half‐wave potential (E1/2 = 0.890 V) and robust long‐term stability. Moreover, the Co40SAs/AC@NG presents excellent performance in Zn–air battery with a high‐peak power density (221 mW cm−2) and strong cycling stability, demonstrating great potential for energy storage applications. [ABSTRACT FROM AUTHOR]

A simple pyrolysis route has been developed for fabrication of nitrogen-doped carbon networks (N-C net) that not only features a large number of mesoporous structures, but also holds high specific surface area and excellent conductivity. The as-developed N-C net performs impressively toward electrocatalysis of oxygen reduction reaction (ORR) and CO 2 reduction reaction (CO 2 RR). For ORR in alkaline electrolyte, the N-C net manifests an initial potential of 0.95 V and half-wave potential of 0.86 V that are comparable to the benchmarked Pt/C catalysts. While for CO 2 RR, the N-C net shows a high selectivity for CO production with Faraday efficiency (FE) of as high as 95% and long-term stability. We further demonstrate the potential application of N-C net in electrochemical devices of zinc-air batteries (ZABs) and microbial CO 2 electrolysis cell (MEC), the former is capable of releasing a maximum power density of 141 mW cm-2, while the later shows capability for efficiently converting CO 2 into CO with the assistance of external voltage. We thus propose and set up an integrated proof-of-concept electrochemical device with ZABs driving MEC that can implement the feasibility of self-powered conversion of CO 2 to value-added CO. [Display omitted] • The N-doped carbon networks prepared by one-pot pyrolyzing ZIF-8 exhibited excellent electrocatalytic properties toward oxygen reaction reduction and CO 2 reduction. • Catalyzed by the cathodic bifunctional N-doped carbon networks, the Zn-air batteries and microbial CO 2 electrolysis cell with favorable performance were assembled in this work. • A coupled electrochemical device with ZABs driving MEC was firstly proposed and achieved self-powered conversion of CO 2 to value-added CO. [ABSTRACT FROM AUTHOR]

Optimized electrocatalyst that hybrids with carbon coating FeCoP x nanoparticles possesses catalytic activity toward ORR, OER and HER. Furthermore, through the design of alkali-acid electrolyzer and device integration, for the very first time, a single Zinc-air battery enable to drive an alkali-acid electrolyzer for producing hydrogen and oxygen. [Display omitted] • A one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst. • High catalytic activity toward ORR&OER in alkaline and HER in acidic media. • The Zn-air battery can run stably for 1500 cycles. • An alkali-acid electrolyzer only requires 0.99 V to release an electrolysis current density of 10 mA cm−2. • A single self-made Zinc-air battery can drive an alkali-acid electrolyzer to produce hydrogen. Developing handy synthesis routes to fabricate low-cost, high-activity, and multifunctional electrocatalysts for a variety of electrochemical reactions is highly desirable so as to achieve the goal that one catalyst can be used for integrated electrolysis devices, thus greatly simplifying the electrocatalyst system processing. Here, we report a one-pot scalable pyrolysis strategy to fabricate a tri-functional electrocatalyst, i.e. , hybrids with carbon coating FeCoP x nanoparticles, which shows favorable electrocatalytic properties toward oxygen reduction reaction, oxygen evolution reaction in alkaline solution, and hydrogen evolution reaction in acidic condition. The new synthesis routes enable us to readily develop an integrated device with a Zn-air battery driving an alkali-acid electrolyzer by just using one catalyst. The present work may shed light on the practical viability of the development of multifunctional electrocatalysts for integrated devices applications. [ABSTRACT FROM AUTHOR]