Organic synthesis chemistry plays a crucial role in supporting social sustainable development and finds widespread applications across various fields. Electrocatalysis, with its benefits of high efficiency, mild reaction conditions, controllability, and environmental friendliness, stands out as one of the most effective strategies for driving the transformation of organic substrates. In recent years, Nanocrystals (NCs) and single atom catalysts (SACs) have garnered significant attention in the realm of electrocatalytic organic transformation. This article presents a comprehensive overview of the applications of NCs and SACs in electrocatalytic organic transformation. It delves into advanced catalysts for electrocatalysis of representative substrates, covering both anodic oxidation and cathodic reduction aspects, and addresses their synthesis, characterization, catalytic mechanism, and performance. The ultimate goal of this review is to serve as a valuable reference and a source of inspiration for further exploration into the development of more effective catalysts for electrocatalytic organic transformation.

As a new water treatment technology, Fenton-like reaction has great potential. In this study, we successfully prepared an excellent Fenton-like catalyst, which is composed of cobalt monoatoms and asymmetric subnanoclusters (labeled CoSA/Clu-C₂N), and exhibits excellent peroxymonosulfate (PMS) activation reactivity. By directly comparing the catalytic properties of CoSA-C₂N and CoSA/Clu-C₂N, the synergistic effects of coasymmetric Co subclusters and Co atoms on the activation of PMS and degradation of organic micropollutants were investigated. The results showed that CoSA/Clu-C₂N had higher degradation rates of carbamazepine (CBZ), antipyrine (AT) and chlorobenzoic acid (CA) when combined with active oxidant PMS. The cyclic frequency of CBZ was 5.4 min⁻¹, which was twice as high as the catalytic constant of CoSA-C₂N (2.4 min⁻¹). The results show that CoSA/Clu-C₂N cobalt subnanoclusters and cobalt single atom can synergistically improve the catalytic performance of activated PMS oxidation of micropollutants in water. In addition, electron paramagnetic resonance (EPR) technology has proved that the introduction of Co subnano clusters in CoSA/Clu-C₂N is conducive to the production of singlet oxygen (¹O₂), thereby improving the efficiency of pollutant oxidation. This work lays a solid foundation for the future design of advanced multifunctional catalysts by carefully regulating and combining monmetallic atoms and metal subnanoclusters.

Tandem catalysis, capable of decoupling individual steps, provides a feasible way to build a high-efficiency CO₂ electro-conversion system for multicarbons (C₂₊). The construction of electrocatalytic materials is one of focusing issues. Herein, we fabricated a single atom involved multivalent oxide-derived Cu composite material and found it inclined to reconstruct into oxygen-deficient multiphase Cu based species hybridized with monatomic Ni on N doped C matrix. In this prototype, rapid CO generation and C−C coupling are successively achieved on NiN₄ sites and surface amorphized Cu species with defects, resembling a micro-production line. In this way, the in situ formed tandem catalyst exhibited a high Faradaic efficiency (FE) of ~ 78% for C₂₊ products along with satisfactory durability over 50 h. Particularly, the reconstruction-induced amorphous layer with abundant asymmetric sites should be favorable to improve the ethanol selectivity (FE: 63%), which is about 10 times higher than that of the non-tandem Cu-based contrast material. This work offers a new approach for manipulating tandem catalyst systems towards enhancing C₂₊ products.

Efficient photocatalysis and electrocatalysis in energy conversion have been important strategies to alleviate energy crises and environmental issues. In recent years, with the rapid development of emerging catalysts, significant progress has been made in photocatalysis for converting solar energy into chemical energy and electrocatalysis for converting electrical energy into chemical energy. However, their selectivity and efficiency of the products are poor. Rare earth (RE) can achieve atomic level fine regulation of catalysts and play an crucial role in optimizing catalyst performance by their unique electronic and orbital structures. However, there is a lack of systematic review on the atomic interface regulation mechanism of RE and their role in energy conversion processes. Single atom catalysts (SACs) provide clear active sites and 100% atomic utilization, which is conducive to exploring the regulatory mechanisms of RE. Therefore, this review mainly takes atomic level doped RE as an example to review and discuss the atomic interface regulation role of RE elements in energy conversion. Firstly, a brief introduction was given to the synthesis strategies that can effectively exert the atomic interface regulation effect of RE, with a focus on the atomic interface regulation mechanism of RE. Meanwhile, the regulatory mechanisms of RE atoms have been systematically summarized in various energy conversion applications. Finally, the challenges faced by RE in energy conversion, as well as future research directions and prospects, were pointed out.

Interface regulation plays a key role in the electrochemical performance for biosensors. By controlling the interfacial interaction, the electronic structure of active species can be adjusted effectively at micro and nano-level, which results in the optimal reaction energy barrier. Herein, we propose an interface electronic engineering scheme to design a strongly coupled 1T phase molybdenum sulfide (1T-MoS₂)/MXene hybrids for constructing an efficient electrocatalytic biomimetic sensor. The local electronic and atomic structures of the 1T-MoS₂/Ti₃C₂T_X are comprehensively studied by synchrotron radiation-based X-ray photoelectron spectroscopy (XPS), as well as X-ray absorption spectroscopy (XAS) at atomic level. Experiments and theoretical calculations show that there are interfacial stresses, atomic defects and adjustable bond-length between MoS₂/MXene nanosheets, which can significantly promote biomolecular adsorption and rapid electron transfer to achieve excellent electrochemical activity and reaction kinetics. The 1T-MoS_2/Ti₃C₂T_X modified electrode shows ultra high sensitivity of 1.198 μA/μM for dopamine detection with low limit of 0.05 μM. We anticipate that the interface electronic engineering investigation could provide a basic idea for guiding the exploration of advanced biosensors with high sensitivity and low detection limit.

Mn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NO_x with NH₃ (NH₃-SCR). However, challenges such as H₂O- or SO₂-induced poisoning to these catalysts still remain. Herein, we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO₂ catalyst via ball-milling and calcination processes to address these issues. Ce-Ti/MnO₂ showed better catalytic performance with a higher NO conversion and enhanced H₂O- and SO₂-resistance at a low-temperature window (100−150 °C) than the MnO₂, single-atom Ce/MnO₂, and Ti/MnO₂ catalysts. The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NO_x and H₂O over the Ce-Ti/MnO₂ catalyst. The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO₂ and H₂O but enhances their binding to NH₃. The insight obtained in this work deepens the understanding of catalysis for NH₃-SCR. The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO₂-based single-atom catalysts.

Although nanozyme has become an emerging area of research attracting extensive attention recently, the activity and specificity of currently reported nanozymes are generally lower than those of natural enzymes. Developing highly active and specific nanozymes is therefore extremely necessary and also remains a great challenge. Superoxide dismutase (SOD) catalyzes the disproportionation of cytotoxic O₂^·− into hydrogen peroxide and oxygen, and plays an important role in reducing human oxidative stress. In this work, we prepare Cu single-atom catalysts (Cu/GO SACs, GO = graphene oxide) through a simple and low-cost strategy at room temperature using Cu foam and graphene oxide. Cu/GO SACs can maintain excellent catalytic activity under harsh environment. Compared with the natural enzyme, SOD-like Cu/GO SAC nanozyme has higher catalytic activity and meanwhile, it does not possess the common properties of other mimic enzymes often existing in nanomaterials. Based on the excellent SOD-like enzyme activity of Cu/GO SACs, it successfully eliminates the active oxygen in cigarette smoke. This work not only provides a new idea for the design and synthesis of nanozymes with excellent SOD mimetic properties, but also is promising in the treatment of lung injury and inflammatory diseases related to free radical production.

Originated from nature and used for nature is a way of sustainable development. In this work, montmorillonite (MMT), a natural two-dimensional (2D) layered mineral, the surface and interlayer of which were nano-decorated by chemical synthesis technique was applied in biological detection field. Magnetic ferrite (Co_0.5Ni_0.5Fe₂O₄) was anchored on the surface and intercalated in the interlayer of montmorillonite, which served as a competitive candidate of enzyme mimics. Cytotoxicity test toward HUVEC and Hela cells verified the good biocompatibility of Co_0.5Ni_0.5Fe₂O₄-MMT, guaranteeing its safety in biological applications. Based on the peroxidase-like activity of Co_0.5Ni_0.5Fe₂O₄-MMT, a colorimetric sensing platform for H₂O₂ was established by a facile mix-and-detect approach with the detection limit of 0.565 μM (3σ/slope). It was implied that the peroxidase-like activity of Co_0.5Ni_0.5Fe₂O₄-MMT was originated from generation of ·OH and ·O₂^– produced from catalytic decomposition process of H₂O₂. Coupled with cascaded catalytic reactions of ACh, a facile and efficient sensing platform for ACh with satisfactory anti-interference ability was established. Thus, all these remarkable features highlighted the superiority of Co_0.5Ni_0.5Fe₂O₄-MMT, and endowed it with a powerful competitiveness in the fields of environmental assessing, biosensing, and disease monitoring.

Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is meaningful but challenging. Herein, a robust three dimensional (3D) hollow CoSe₂@ultrathin MoSe₂ core@shell heterostructure (CoSe₂@MoSe₂) is proposed as an efficient HER electrocatalyst through interfacial engineering. Benefitting from the abundant heterogeneous interfaces on CoSe₂@MoSe₂, the exposed edge active sites are maximized and the charge transfer at the hetero-interfaces is accelerated, thus facilitating the HER kinetics. It exhibits remarkable performance in pH-universal conditions. Notably, it only needs an overpotential (η₁₀) of 108 mV to reach a current density of 10 mA·cm⁻² in 1.0 M KOH, outperforming most of the reported transition metal selenides electrocatalysts. Density functional theory (DFT) calculations unveil that the heterointerfaces synergistically optimize the Gibbs free energies of H₂O and H* during alkaline HER, accelerating the reaction kinetics. The present work may provide new construction guidance for rational design of high-efficient electrocatalysts.

As an alternative energy, hydrogen can be converted into electrical energy via direct electrochemical conversion in fuel cells. One important drawback of full cells is the sluggish oxygen reduction reaction (ORR) promoted by the high-loading of platinum-group-metal (PGM) electrocatalysts. Fe-N-C family has been received extensive attention because of its low cost, long service life and high oxygen reduction reaction activity in recent years. In order to further enhance the ORR activity, the synthesis method, morphology regulation and catalytic mechanism of the active sites in Fe-N-C catalysts are investigated. This paper reviews the research progress of Fe-N-C from nanoparticles to single atoms. The structure-activity relationship and catalytic mechanism of the catalyst are studied and discussed, which provide a guidance for rational design of the catalyst, so as to promote the more reasonable design of Fe-N-C materials.