Electrochemical CO 2 reduction (CO 2 RR) using renewable energy sources represents a sustainable means of producing carbon-neutral fuels. Unfortunately, low energy efficiency, poor product selectivity, and rapid deactivation are among the most intractable challenges of CO 2 RR electrocatalysts. Here, we strategically propose a "two ships in a bottle" design for ternary Zn−Ag−O catalysts, where ZnO and Ag phases are twinned to constitute an individual ultrafine nanoparticle impregnated inside nanopores of an ultrahigh-surface-area carbon matrix. Bimetallic electron configurations are modulated by constructing a Zn−Ag−O interface, where the electron density reconfiguration arising from electron delocalization enhances the stabilization of the *COOH intermediate favorable for CO production, while promoting CO selectivity and suppressing HCOOH generation by altering the rate-limiting step toward a high thermodynamic barrier for forming HCOO*. Moreover, the pore-constriction mechanism restricts the bimetallic particles to nanosized dimensions with abundant Zn−Ag−O heterointerfaces and exposed active sites, meanwhile prohibiting detachment and agglomeration of nanoparticles during CO 2 RR for enhanced stability. The designed catalysts realize 60.9% energy efficiency and 94.1 ± 4.0% Faradaic efficiency toward CO, together with a remarkable stability over 6 days. Beyond providing a high-performance CO 2 RR electrocatalyst, this work presents a promising catalyst-design strategy for efficient energy conversion.

Atomically dispersed metal catalysts are hailed as the most promising catalyst category for oxygen electrocatalysis. However, the challenges in regulating electronic configuration and unveiling the mechanism on the atomic scale are hindering their practical implementation. Herein, we modulate the Co d-orbital electron configuration by constructing the Ir−Co atomic pair toward boosted bifunctional activity. The as-developed dual-atom IrCo− N−C catalyst displays unprecedented activity with a half-wave potential of 0.911 V for oxygen reduction reaction and only 330 mV overpotential at 10 mA cm −2 for oxygen evolution reaction, outperforming the single-atom counterparts as well as the commercial Pt/C and Ir/C benchmarks. The impressive bifunctionality is also verified in a Zn−air battery prototype with an ultra-high cyclability over 450 cycles. Theoretical calculations are performed to shed light on the synergetic effects of the atomic pair site, where the incorporation of Ir atom alters the d-orbital energy level of Co and thus induces the re-arrangement of d-electron toward intensified spin polarization. As a result, the lower occupancy of d z 2 orbital facilitates the electron acceptation from oxygen to form a stronger Co−O σ bond, thereby propelling faster reaction kinetics.

Graphene quantum dots (GQDs) have aroused great interest in the scientific community in recent years due to their unique physicochemical properties and potential applications in different fields. To date, much research has been conducted on the ingenious design and rational construction of GQDs‐based nanomaterials used as electrode materials and/or electrocatalysts. Despite these efforts, research on the efficient synthesis and application of GQDs‐based nanomaterials is still in the early stages of development and timely updates of recent research progress on new design concepts, synthetic strategies, and significant breakthroughs in GQDs‐based nanomaterials are highly desired. In light of the above, the effect of synthetic methods on the final product of the GQDs, the GQDs synthesis mechanism, and specific perspectives regarding the effect of the unique surface and structural properties of GQDs (e.g., defects, heteroatom doping, surface/edge state, size, conductivity) on the electrochemical energy‐related systems are discussed in‐depth in this review. Additionally, this review also focuses on the design of GQDs‐based composites and their applications in the fields of electrochemical energy storage (e.g., supercapacitors and batteries) and electrocatalysis (e.g., fuel cell, water splitting, CO2 reduction), along with constructive suggestions for addressing the remaining challenges in the field.

Oxygen‐related electrocatalysis, including those used for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), play a central role in green‐energy related technologies. Rational fabrication of effective oxygen electrocatalysts is crucial for the development of oxygen related energy devices, such as fuel cells and rechargeable metal–air batteries. Recently, owing to their tunable compositions and microstructures, metal–organic frameworks (MOFs) based materials have drawn extensive attention as nonprecious oxygen electrocatalysts. Various strategies have been developed to fabricate MOF‐based electrocatalysts and regulate their active sites, such as heterometal doping, defect engineering, morphology tuning, heterostructure construction, and hybridization. In this review, by focusing on various modulation strategies aiming at active sites, the recent advances of MOF‐based electrocatalysts are summarized. The synthetic methods used to synthesize various MOF‐based oxygen electrocatalysts are discussed, followed by the underlying engineering mechanisms required to allow performance enhancement, and finally some existing challenges that hinder for their practical applications are discussed alongside a perspective on their possible future.

We experimentally investigate the electromagnetic (EM) responses of a broadband reflective polarization rotator under normal incidence. It is found that the rotator can generate multi-order plasmon resonances at three neighboring frequencies. At each frequency, the rotator behaves as a high impedance surface along one axis while as a metallic reflective surface along the other axis. Thus, a 180° phase difference is generated between the two orthogonal components of reflected waves. When the incident wave is polarized by 45° with respect to the symmetry axis of the rotator, the polarization of reflected waves is rotated by 90°. The designed rotator presents broadband properties. It can perform perfect 90° polarization rotation at three frequencies and maintains a polarization conversion efficiency greater than 56% in 2.0–3.5 GHz. The rotator provides a route to broadband polarization rotation and has application values in polarization control.

Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co-ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy-efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode-based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research.

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Efficient coupling solar energy conversion and N 2 fixation by photocatalysis has been shown promising potentials.H owever,t he unsatisfied yield rate of NH 3 curbs its forwarda pplication. Defective typical perovskite,B aTiO 3 , shows remarkable activity under an applied magnetic field for photocatalytic N 2 fixation with an NH 3 yield rate exceeding 1.93 mg L À1 h À1 .T hrough steered surface spin states and oxygen vacancies,t he electromagnetic synergistic effect between the internal electric field and an external magnetic field is stimulated. X-raya bsorption spectroscopya nd density functional theory calculations reveal the regulation of electronic and magnetic properties through manipulation of oxygen vacancies and inducement of Lorentz force and spin selectivity effect. The electromagnetic effect suppresses the recombination of photoexcited carriers in semiconducting nanomaterials, which acts synergistically to promote N 2 adsorption and activation while facilitating fast charge separation under UVvis irradiation.