Electrocatalytic nitrate reduction reaction (NitRR) is an efficient route for simultaneous wastewater treatment and ammonia production, but the conversion of NO₃^- to NH₃ involves multiple electron and proton transfer processes and diverse by-products. Therefore, developing ammonia catalysts with superior catalytic activity and selectivity is an urgent task. The distinctive electronic structure of Cu enhances the adsorption of nitrogen-containing intermediates, but the insufficient activation capability of Cu for interfacial water restricts the generation of reactive hydrogen and inhibits the hydrogenation process. In this work, a Ce-doped CuO catalyst (Ce₁₀/CuO) was synthesized by in situ oxidative etching and annealing. The redox of Ce³⁺/Ce⁴⁺ enables the optimization of the electronic structure of the catalyst, and the presence of Ce³⁺ as a defect indicator introduces more oxygen vacancies. The results demonstrate that Ce₁₀/CuO provides an impressive ammonia yield of 3.88 (± 0.14) mmol cm^-2 h^-1 at 0.4 V vs. RHE with an increase of 1.04 mmol cm^-2 h^-1 compared to that of pure CuO, and the FE reaches 93.2% (± 3.4). In situ characterization confirms the doping of Ce facilitates the activation and dissociation of interfacial water, which promotes the production of active hydrogen and thus enhances the ammonia production efficiency.

Electrocatalytic chemical oxidation (ECO) is an energy-efficient anodic reaction alternative to the oxygen evolution reaction (OER). ECO lowers the reaction potential and yields higher-value fine chemicals at the anode. The catalyst material plays a crucial role in influencing and determining ECO performance. Enhancing catalyst performance encompasses aspects such as activity, stability, selectivity, and cost. Nickel-based electrocatalysts have garnered significant attention for their exceptional performance and widespread use in ECO applications. By modifying Nickel-based electrocatalysts, the formation of NiOOH active centers can be encouraged. Strategies such as adjusting size and morphology, doping, introducing defects, and constructing heterojunctions are advantageous for enhancing performance. Given the rapid advancements in related research fields, it is imperative to comprehend the mechanisms of nickel-based electrocatalysts in ECO and develop innovative catalysts. This article provides an overview of the modification strategies of nickel-based electrocatalysts, as well as their applications and mechanisms in ECO.

Electrochemical carbon dioxide reduction reaction (CO₂RR) can produce value-added hydrocarbons from renewable electricity, providing a sustainable and promising approach to meet dual-carbon targets and alleviate the energy crisis. However, it is still challenging to improve the selectivity and stability of the products, especially the C₂₊ products. Here we propose to modulate the electronic structure of copper oxide (CuO) through lattice strain construction by zinc (Zn) doping to improve the selectivity of the catalyst to ethylene. Combined performance and in situ characterization analyses show that the compressive strain generated within the CuO lattice and the electronic structure modulation by Zn doping enhances the adsorption of the key intermediate *CO, thereby increasing the intrinsic activity of CO₂RR and inhibiting the hydrogen precipitation reaction. Among the best catalysts had significantly improved ethylene selectivity of 60.5% and partial current density of 500 mA·cm^–2, and the highest C₂₊ Faraday efficiency of 71.47%. This paper provides a simple idea to study the modulation of CO₂RR properties by heteroatom doped and lattice strain.

The electrochemical nitrate reduction reaction (NO₃RR) to ammonia under ambient conditions is a promising approach for addressing elevated nitrate levels in water bodies, but the progress of this reaction is impeded by the complex series of chemical reactions involving electron and proton transfer and competing hydrogen evolution reaction. Therefore, it becomes imperative to develop an electro-catalyst that exhibits exceptional efficiency and remarkable selectivity for ammonia synthesis while maintaining long-term stability. Herein the magnetic biochar (Fe-C) has been synthesized by a two-step mechanochemical route after a pyrolysis treatment (450, 700, and 1000 °C), which not only significantly decreases the particle size, but also exposes more oxygen-rich functional groups on the surface, promoting the adsorption of nitrate and water and accelerating electron transfer to convert it into ammonia. Results showed that the catalyst (Fe-C-700) has an impressive NH₃ production rate of 3.5 mol·h⁻¹·g_cat⁻¹, high Faradaic efficiency of 88%, and current density of 0.37 A·cm⁻² at 0.8 V vs. reversible hydrogen electrode (RHE). In-situ Fourier transform infrared spectroscopy (FTIR) is used to investigate the reaction intermediate and to monitor the reaction. The oxygen functionalities on the catalyst surface activate nitrate ions to form various intermediates (NO₂, NO, NH₂OH, and NH₂) and reduce the rate determining step energy barrier (*NO₃ → *NO₂). This study presents a novel approach for the use of magnetic biochar as an electro-catalyst in NO₃RR and opens the road for solving environmental and energy challenges.

The development of efficient non-precious metal catalysts is important for the large-scale application of alkaline hydrogen evolution reaction (HER). Here, we synthesized a composite catalyst of Cu and Mo₂C (Cu/Mo₂C) using Anderson-type polyoxometalates (POMs) synthesized by the facile soaking method as precursors. The electronic interaction between Cu and Mo₂C drives the positive charge of Cu, alleviating the strong adsorption of hydrogen at the Mo site by modulating the d-band center of Mo₂C. By studying the interfacial water structure using in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), we determined that the positively charged Cu crystals have the function of activating water molecules and optimizing the interfacial water structure. The interfacial water of Cu/Mo₂C contains a large amount of free water, which could facilitate the transport of reaction intermediates. Due to activated water molecules and optimized interfacial water structure and hydrogen adsorption energy, the overpotential of Cu/Mo₂C is 24 mV at a current density of 10 mA·cm⁻² and 178 mV at a current density of 1000 mA·cm⁻². This work improves catalyst performance in terms of interfacial water structure optimization and deepens the understanding of water-mediated catalysis.

The microstructure design of electrode material is a crucial point to optimize the supercapacitor’s electrochemical properties. In this work, a Bi-based nanocomposite with a three-layer structure (Bi–Bi₂O₃@carbon armour (CA)/carbon dots (CDs)) is synthesized and investigated. This material inherits high capacitance and high activity from bismuth-based materials, and the coated CA protects the structure from complete oxidization and improves surface hydrophilicity. Furthermore, CDs in CA can enhance the ion conduction efficiency between the catalyst, carbon membrane, and electrolyte. As a consequence, the specific capacitance of the electrode reaches 973 F·g⁻¹ under 1 A·g⁻¹, and the energy density achieves 32.5 Wh·kg⁻¹ with a power density of 266.9 W·kg⁻¹, with impressive electrochemical stability that Coulomb efficiency of the electrode remains about 100% after 5000 cycles. Furthermore, in-situ Fourier transformation infrared (FT-IR) analyzes the structure evolvement of the material during synthesis and finds that the annealing process of the material removes a great number of oxygen-containing groups of CA and CDs, generating oxygen vacancies, defects, and thus active sites, which enhance the capacitance of the material.

Photocatalytic reduction of carbon dioxide into valuable chemicals is a sustainable and promising technology that alleviates the greenhouse effect and energy crisis. In this study, the Mn₃O₄/FeNbO₄ type II heterojunction photocatalyst with a core-satellite structure was synthesized by the facile soft chemical method. The formation of a nano-heterojunction is supposed to effectively improve light capture, charge transfer, and interfacial charge separation in the photochemical reaction. Meanwhile, the heterojunction has a good ability to capture and activate CO₂. Our results show that the prepared Mn₃O₄/FeNbO₄ photocatalyst exhibit obvious enhanced catalytic properties in the photocatalytic CO₂ reduction reaction, where the CH₄ yielding rate is 1.96 and 9.81 times those of FeNbO₄ and Mn₃O₄, respectively. The transient photovoltage test (TPV) shows that the low frequency electrons are crucial to the effective transfer of photogenerated electrons and holes in the Mn₃O₄/FeNbO₄ nano heterojunctions. Analysis of in situ Fourier transform infrared spectroscopy (FTIR) verifies the effective CO₂ adsorption on the Mn₃O₄/FeNbO₄ surface and the high selectivity of CH₄ products. These properties of the Mn₃O₄/FeNbO₄ photocatalyst infer its broad prospects in the fields of carbon fixation and energy conservation.

Ammonia plays a vital role in the development of modern agriculture and industry. Compared to the conventional Haber–Bosch ammonia synthesis in industry, electrocatalytic nitrogen reduction reaction (NRR) is considered as a promising and environmental friendly strategy to synthesize ammonia. Here, inspired by biological nitrogenase, we designed iron doped tin oxide (Fe-doped SnO₂) for nitrogen reduction. In this work, iron can optimize the interface electron transfer and improve the poor conductivity of the pure SnO₂, meanwhile, the synergistic effect between iron and Sn ions improves the catalyst activity. In the electrocatalytic NRR test, Fe-doped SnO₂ exhibits a NH₃ yield of 28.45 μg·h⁻¹·mg_cat⁻¹, which is 2.1 times that of pure SnO₂, and Faradaic efficiency of 6.54% at −0.8 V vs. RHE in 0.1 M Na₂SO₄. It also shows good stability during a 12-h long-term stability test. Density functional theory calculations show that doped Fe atoms in SnO₂ enhance catalysis performance of some Sn sites by strengthening N–Sn interaction and lowering the energy barrier of the rate-limiting step of NRR. The transient photovoltage test reveals that electrons in the low-frequency region are the key to determining the electron transfer ability of Fe-doped SnO₂.

As photothermal conversion agents, carbon nanomaterials are widely applied in polymers for light-triggered shape memory behaviors on account of their excellent light absorption. However, they are usually derived from non-renewable fossil resources, which go against the demand for sustainable development. Biomass-derived carbon nanomaterials are expected as alternatives if they are designed with good dispersibility as well as splendid photothermal properties. Up to date, very few researches focused on this area. Herein, we report a novel light-triggered shape memory composite by incorporating renewable biomass-derived carbon nanomaterials into acrylate polymers without deep purification and processing. These functionalized carbon nanomaterials not only have stable dispersion in polymers as fillers, but also can endow the polymers with excellent and stable thermal and photothermal responsive properties in biological friendly environment. With the introduction of biomass-derived carbon nanomaterials, the mechanical properties of the composites are also further enhanced with the formation of hydrogen bonding between the carbon nanomaterials and the polymers. Notably, the doping of 1% carbon nanomaterials endows the polymer with sufficient hydrogen bonds that not only exhibit excellent thermal and photothermal responsive properties, but also with enough space for the motion of chains. These properties make such composite a promising and safe candidate for shape memory applications, which provide a new avenue in smart fabrics or intelligent soft robotics.