The electrochemical conversion of carbon dioxide (CO₂) into chemical fuels represents a promising approach for addressing global carbon balance issues. However, this process is hindered by the kinetic limitations of anodic reactions, usually the oxygen evolution reaction, resulting in less efficient production of high value-added products. Here, we report an integrated electrocatalytic system that couples CO₂ reduction reaction (CO₂RR) with urea oxidation reaction (UOR) using a bifunctional electrocatalyst with atomically dispersed dual-metal CuNi sites anchored on bamboo-like nitrogen-doped carbon nanotubes (CuNi-CNT), which were synthesized through a one-step pyrolysis process. The bifunctional CuNi-CNT catalyst exhibits a near 100% CO Faraday efficiency for CO₂RR over a wide potential range, and outstanding UOR performance with a negatively shifted potential of 210 mV at at 10 mA·cm⁻². In addition, we assemble a two-electrode electrolyzer using bifunctional CuNi-CNT-modified carbon fiber paper electrodes as both cathode and anode, capable of operating at a remarkably low cell voltage of 1.81 V at 10 mA·cm⁻², significantly lower than conventional setups. The study provides a novel avenue to achieving an efficient carbon cycle with reduced electric power consumption.

The electrocatalytic nitrogen reduction reaction (e-NRR) is a promising alternative method for the Haber–Bosch process. However, it still faces many challenges in searching for high activity, stability, and selectivity catalysts and ascertaining the catalytic mechanism with complete insight. Here, a series of graphene-based N-bridged dual-atom catalysts (M1-N-M2/NC) are systematically investigated via first-principle calculation and a high-throughput screening strategy. The result unveils that N₂ adsorption on M1-N-M2/NC in bridge-on adsorption mode can effectively break the scaling relationship on single-atom catalysts (SACs). Moreover, V-N-Ru/NC and V-N-Os/NC are systematically screened out as promising e-NRR catalysts, with extremely low limiting potentials of −0.20 and −0.18 V, respectively. Furthermore, the adsorption site competition between *N₂ and *H, as well as the competitive twin reactions of hydrogen evolution reaction (HER) on intermediates (N_nH_m) during the e-NRR process, is systematically evaluated to form a remodeling insight for the reactions in mechanism, and the e-NRR of new proposed dual-atom catalysts (DACs) is strategically optimized for its high-efficiency performance potential via our remolding insight in e-NRR mechanism. This work provides new ideas and insights for the design and mechanism of e-NRR catalysts and an effective strategy for rapidly screening highly efficient e-NRR catalysts.

Due to their rich and adjustable porous network structure, paper-based functional materials have become a research hotspot in the field of energy storage. However, reasonably designing and making full use of the rich pore structure of paper-based materials to improve the electrochemical performance of paper-based energy storage devices still faces many challenges. Herein, we propose a structure engineering technique to develop a conductive integrated gradient porous paper-based (CIGPP) supercapacitor, and the kinetics process for the influence of gradient holes on the electrochemical performance of the CIGPP is investigated through experimental tests and COMSOL simulations. All results indicate that the gradient holes endow the CIGPP with an enhanced electrochemical performance. Specifically, the CIGPP shows a significant improvement in the specific capacitance, displays rich frequency response characteristics for electrolyte ions, and exhibits a good rate performance. Also, the CIGPP supercapacitor exhibits a low self-discharge and maintains a stable electrochemical performance in different electrolyte environments because of gradient holes. More importantly, when the CIGPP is used as a substrate to fabricate a CIGPP-PANI hybrid, it still maintains good electrochemical properties. In addition, the CIGPP supercapacitor also shows excellent stability and sensitivity for monitoring human motion and deaf-mute voicing, showing potential application prospects. This study provides a reference and feasible way for the design of structure-engineered integrated paper-based energy storage devices with outstanding comprehensive electrochemical performance.

Photocatalysis is considered as an effective technique for mitigating ecological risks posed by residual tetracycline (TC). To improve the efficiency of this technique, it is necessary to enable photocatalysts to produce highly reactive species, such as singlet oxygen (¹O₂). However, due to the high activation energy of ¹O₂, photocatalysts can hardly produce ¹O₂ without assistance from external oxidants. Herein, we find that the size-reduced α-Fe₂O₃ nanoparticles (~ 4 nm) that anchored on g-C₃N₄ nanotube (α-Fe₂O₃@CNNT) can spontaneously generate ¹O₂ for degradation of TC. In comparison, only hydroxyl radical (·OH) can be produced by g-C₃N₄ nanotube loaded with ~ 14 nm α-Fe₂O₃ nanoparticles (α-Fe₂O₃/CNNT). Owing to the high reactivity of the ¹O₂ species, the photocatalytic degradation rate (K_app) of TC with α-Fe₂O₃@CNNT (0.056 min⁻¹) was 1.8 times higher than that of α-Fe₂O₃/CNNT. The experimental results and theoretical calculations suggested that reducing the size of α-Fe₂O₃ nanoparticles anchored on g-C₃N₄ nanotube decreased the surface electron density of α-Fe₂O₃, which induces the generation of high-valent Fe(IV) active sites over α-Fe₂O₃@CNNT and turns the degradation pathway into a unique ¹O₂ dominated process. This study provides a new insight on the generation of ¹O₂ for effective degradation of environmental pollutant.

In heterogeneous catalytic reactions, supported metal catalysts have attracted increasing attention for the environmental remediation and industrial manufacture due to their inherent catalytic capacity. However, leaching, agglomeration, and poisoning of active metal particles lead to catalyst deactivation, thereby limiting their applications. To avoid this, strategies to protect the active metals from such inactivating processes are major areas of research. Emerging encapsulation strategies, in which active species are coated by protective shells, have proven to be a powerful technology to enhance catalytic performance by creating a well-developed structure about the active catalytic sites. This review highlights the recent advances on preparation method and application of encapsulated catalysts since 2016. Building upon the traditional confinement effect, new categories and extended concepts of encapsulation are introduced. In parallel, effects of encapsulation structure on performance and key factors controlling the structure of encapsulated catalyst are discussed definitely in this review. Finally, future perspectives on opportunities and challenges for further research in the field are given at the end of this paper.

High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance, but still challenging. Herein, a new strategy, consisting of using diatomic synergistic modulation (DSM) to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported. The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH₂ photocatalyst (Fe₁/Cr:MIL-53-NH₂) is designed, in which Cr single atoms are substituted for Al³⁺ while Fe single atoms are coordinated by N. Notably, the Fe₁/Cr:MIL-53-NH₂ significantly boosts the photo-oxidation of benzene to phenol under visible light irradiation, which is much higher than those of MIL-53-NH₂, Cr:MIL-53-NH₂, Fe₁/MIL-53-NH₂, and Fe nanoparticles/Cr:MIL-53-NH₂ catalysts. Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor, respectively, during photocatalytic reaction, exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation. This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.

Atomically dispersed metals stabilized by nitrogen elements in carbon skeleton hold great promise as alternatives for Pt-based catalysts towards oxygen reduction reaction in proton exchange membrane fuel cells. However, their widespread commercial applications are limited by complicated synthetic procedures for mass production. Herein, we are proposing a simple, green mechanochemical approach to synthesize zeolitic imidazolate frameworks precursors for the production of atomically dispersed “Fe-N₄” sites in holey carbon nanosheets on a large scale. The thin porous carbon nanosheets (PCNs) with atomically dispersed “Fe-N₄” moieties can be prepared in hectogram scale by directly pyrolysis of salt-sealed Fe-based zeolitic imidazolate framework-8 (Fe-ZIF-8@NaCl) precursors. The PCNs possess large specific surface area, abundant lamellar edges and rich “Fe-N₄” active sites, and show superior catalytic activity towards oxygen reduction reaction in an acid electrolyte. This work provides a promising approach to cost-effective production of atomically dispersed transition metal catalysts on large scale for practical applications.

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction (ORR) is intensively increasing. Herein, single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst (Cu₁/NC) was prepared by coordination pyrolysis strategy. Remarkably, the Cu₁/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V (vs. RHE) in alkaline media, outperforming those of commercial Pt/C (0.851 V) and Cu nanoparticles anchored on N-doped porous carbon (CuNPs/NC-900), but also demonstrates high stability and methanol tolerance. Moreover, the Cu₁/NC-900 based Zn-air battery exhibits higher power density, rechargeability and cyclic stability than the one based on Pt/C. Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cu₁/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect, resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process. This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.