Understanding electron structure of covalent triazine framework embraced with gold nanoparticles for nitrogen reduction to ammonia

Regulating the electron structure and precise loading sites of metal-active sites within the highly conjugated and porous covalent-triazine frameworks (CTFs) is essential to promoting the nitrogen reduction reaction (NRR) performance for electrocatalytic ammonia (NH3) synthesis under ambient conditions. Herein, experimental method and density functional theory (DFT) calculations were conducted to deeply probe the effect on NRR of the modulation of modulating the electron structure and the loading site of gold nanoparticles (Au NPs) in a two-dimensional (2D) CTF. 2D CTF synthesized using melem and hexaketocyclohexane octahydrate as building blocks (denoted as M-HCO-CTF) served as a robust scaffold for loading Au NPs to form an M-HCO-CTF@AuNP hybrid. DFT results uncovered that well-defined Au sites with tunable local structure were the active site for driving the NRR, which can significantly suppress the conversion of H+ into *H adsorption and enhance the nitrogen (N2) adsorption/activation. The overlapped Au (3d) and *N2 (2p) orbitals lowered the free energy of the rate-determining step to form *NNH, thereby accelerating the NRR. The M-HCO-CTF@AuNPs electrocatalyst exhibited a large NH3 yield rate of 66.3 μg h-1 mg-1cat. and a high Faraday efficiency of 31.4 % at - 0.2 V versus reversible hydrogen electrode in 0.1 M HCl, superior to most reported CTF-based ones. This work can provide deep insights into the modulation of the electron structure of metal atoms within a porous organic framework for artificial NH3 synthesis through NRR.

Atomically Dispersed Ru-doped Ti4O7 Electrocatalysts for Chlorine Evolution Reaction with a Universal Activity

Chlorine has been supplied by the chlor-alkali process that deploys dimensionally stable anodes (DSAs) for the electrochemical chlorine evolution reaction (ClER). The paramount bottlenecks have been ascribed to an intensive usage of precious elements and inevitable competition with the oxygen evolution reaction. Herein, a unique case of Ru2+-O4 active motifs anchored on Magnéli Ti4O7 (Ru-Ti4O7) via a straightforward wet impregnation and mild annealing is reported. The Ru-Ti4O7 performs radically active ClER with minimal deployment of Ru (0.13 wt%), both in 5 m NaCl (pH 2.3) and 0.1 m NaCl (pH 6.5) electrolytes. Scanning electrochemical microscopy demonstrates superior ClER selectivity on Ru-Ti4O7 compared to the DSA. Operando X-ray absorption spectroscopy and density functional theory calculations reveal a universally active ClER (over a wide range of pH and [Cl-]), through a direct adsorption of Cl- on Ru2+-O4 sites as the most plausible pathway, together with stabilized ClO* at low [Cl-] and high pH.

Unveiling Cutting-Edge Developments in Electrocatalytic Nitrate-to-Ammonia Conversion

The excessive enrichment of nitrate in the environment can be converted into ammonia (NH3) through electrochemical processes, offering significant implications for modern agriculture and the potential to reduce the burden of the Haber-Bosch (HB) process while achieving environmentally friendly NH3 production. Emerging research on electrocatalytic nitrate reduction (eNitRR) to NH3 has gained considerable momentum in recent years for efficient NH3 synthesis. However, existing reviews on nitrate reduction have primarily focused on limited aspects, often lacking a comprehensive summary of catalysts, reaction systems, reaction mechanisms, and detection methods employed in nitrate reduction. This review aims to provide a timely and comprehensive analysis of the eNitRR field by integrating existing research progress and identifying current challenges. This review offers a comprehensive overview of the research progress achieved using various materials in electrochemical nitrate reduction, elucidates the underlying theoretical mechanism behind eNitRR, and discusses effective strategies based on numerous case studies to enhance the electrochemical reduction from NO3 - to NH3. Finally, this review discusses challenges and development prospects in the eNitRR field with an aim to guide design and development of large-scale sustainable nitrate reduction electrocatalysts.

FeP-Fe3O4 nanospheres for electrocatalytic N2 reduction to NH3 under ambient conditions

The electrocatalytic nitrogen reduction reaction (eNRR) under ambient conditions is deemed a promising alternative for NH3 synthesis. In this paper, an FeP-Fe3O4 nanocomposite electrocatalyst was prepared by phosphating annealing using Fe2O3 as a precursor, and the resulting FeP-Fe3O4 exhibited excellent N2-to-NH3-producing activity over a wide potential window. The highest faradaic efficiency of FeP-Fe3O4 is 11.02% at -0.1 V vs. reversible hydrogen electrode (RHE), and the maximum NH3 yield reaches 12.73 μg h-1 mgcat-1, comparable to or exceeding the reported values in this field. Furthermore, the FeP-Fe3O4 nanocomposite electrocatalyst presents high electrochemical stability, selectivity, and durability.

Photoelectrochemical-driven nitrogen reduction to ammonia by a Vo-SnO2/TiO2 composite electrode

N2 molecules with the NN triple bond structure are difficult to cleave under mild conditions to achieve the nitrogen fixation reaction. Photoelectrochemical (PEC) catalysis technology combining the advantages of photocatalysis and electrocatalysis provides the possibility of the nitrogen reduction reaction under ambient conditions. Herein, an SnO2/TiO2 photoelectrode was first fabricated through depositing SnO2 quantum dots on TiO2 nanorod arrays via a simple hydrothermal method. The oxygen vacancy (Vo) content was then induced in SnO2 through annealing SnO2/TiO2 at high temperature under an inert atmosphere. The heterogeneous structure of Vo-SnO2 quantum dots and TiO2 nanorods boosted the separation of photocarriers. The photoelectrons generated by photoexcitation were transferred from the conduction band of TiO2 to the conduction band of Vo-SnO2 and trapped by Vo. Vo activates N2 molecules adsorbed on the catalyst surface, and reacts with H+ in the electrolyte to generate NH3. The nitrogen fixation yield of PEC catalysis and its faradaic efficiency can reach 19.41 μg cm-2 h-1, and 59.6% at -0.2 V bias potential, respectively. The heterogeneous structure of Vo-SnO2/TiO2, introduction of Vo and synergistic effect between light and electricity greatly promotes the PEC nitrogen reduction to NH3.

Electrocatalytic reduction of nitrite to ammonia on undercoordinated Cu

Electrocatalytic NO2--to-NH3 reduction (NO2RR) has emerged as an intriguing route for simultaneous mitigation of harmful nitrites and production of valuable NH3. Herein, we design for the first time undercoordinated Cu nanowires (u-Cu) as an efficient and selective NO2RR electrocatalyst, delivering the maximum NO2--to-NH3 faradaic efficiency of 94.7% and an ammonia production rate of 494.5 μmol h-1 cm-2 at -0.7 V vs. RHE. Theoretical calculations reveal that the created undercoordinated Cu sites on u-Cu can enhance NO2- adsorption, boost NO2--to-NH3 energetics and restrict competitive hydrogen evolution, thereby enabling the active and selective NO2RR.

Promoting Nitrite-to-Ammonia Electroreduction over Amorphous CoS2 Nanorods

Electrocatalytic nitrite reduction to ammonia (NO2RR) emerges as a promising route to simultaneously attain harmful NO2- removal and green NH3 synthesis. In this study, amorphous CoS2 nanorods (a-CoS2) are first demonstrated as an effective NO2RR catalyst, which exhibits the maximum FENH3 of 88.7% and NH3 yield rate of 438.1 μmol h-1 cm-2 at -0.6 V vs RHE. Detailed experimental and computational investigations reveal that the high NO2RR performance of a-CoS2 originates from the amorphization-induced S vacancies to facilitate NO2- activation and hydrogenation, boost the electron transport kinetics, and inhibit the competitive hydrogen evolution.

Aloe vera-derived graphene-coupled phenosafranin photocatalyst for generation and regeneration of ammonia and NADH by mimicking natural photosynthetic route

Aloe vera-derived graphene (ADG) coupled system photocatalyst, mimicking natural photosynthesis, is one of the most promising ways for converting solar energy into ammonia (NH3 ) and nicotinamide adenine dinucleotide (NADH) that have been widely used to make the numerous chemicals such as fertilizer and fuel. In this study, we report the synthesis of the aloe vera-derived graphene-coupled phenosafranin (ADGCP) acting as a highly efficient photocatalyst for the generation of NH3 and regeneration of NADH from nitrogen (N2 ) and oxidized form of nicotinamide adenine dinucleotide (NAD+ ). The results show a benchmark instance for mimicking natural photosynthesis activity as well as the practical applications for the solar-driven selective formation of NH3 and the regeneration of NADH by using the newly designed photocatalyst.

Rational design of artificial Lewis pairs coupling with polyethylene glycol for efficient electrochemical ammonia synthesis

Ammonia (NH3) synthesis at mild conditions by electrocatalytic nitrogen reduction (eNRR) has received more attention and has been regarded as a promising alternative to the traditional Haber-Bosch process. Lewis acid-base pairs (LPs) can chemisorb and react with nitrogen by electronic interaction, while the tuning of the microenvironment near electrode can hinder hydrogen evolution reaction (HER) thus improving the selectivity of the eNRR. Herein, the FeOOH nanorod coupled with LPs on the surface (i.e., Fe, Fe-O) was synthesized, which could effectively drive eNRR. Meanwhile, polyethylene glycol (PEG) was introduced to serve as a local non-aqueous electrolyte system to inhibit HER. The prepared FeOOH-150 catalyst achieved outstanding eNRR performance with an NH3 yield rate of 118.07 μg h-1mgcat-1 and a Faradaic efficiency of 51.4 % at -0.6 V vs. RHE in 0.1 M LiClO4 + 20 % PEG. Both the experiment and DFT calculations revealed that the interaction of PEG with Lewis base sites could optimize nitrogen adsorption configuration and activation.

Oxygen Vacancy Engineering of Fe-Doped NiMoO4 for Electrocatalytic N2 Fixation to NH3

Electrochemical nitrogen reduction reaction (NRR) is a promising method for ammonia synthesis under ambient conditions. However, the NRR performance is limited to an extremely strong N≡N bond in N2 and the competing hydrogen evolution reaction. Introducing oxygen vacancies (OVs) has been considered as a forceful means to accelerate the sluggish NRR reaction kinetics. Herein, we reported the design of Fe-doped NiMoO4 catalysts for NRR. Fe doping can increase the amount of OVs in the catalyst and contribute to lattice strain enhancement, thereby leading to the improvement of the electron transport rate and catalytic active for NRR. In 0.1 M Na2SO4 solution, the 5% Fe-NiMoO4 catalyst achieves a NH3 yield rate of 15.36 μg h-1 mgcat.-1 and a Faradaic efficiency of 26.85% under -0.5 V versus RHE. Furthermore, the 5% Fe-NiMoO4 catalyst exhibits excellent stability (up to 13 h) during the reaction.

Charge transfer and vacancy engineering of Fe2O3 nanoparticle catalysts for highly selective N2 reduction towards NH3 synthesis

The development of electrocatalysts for N₂ reduction reaction (NRR) is significant for scalable and renewable NH₃ synthesis, but calls for a technology innovation to overcome the specific problems of low efficiency and poor selectivity. Herein, we prepare a core-shell nanostructure by coating polypyrrole (PPy) onto sulfur-doped iron oxide nanoparticles (denoted as S-Fe₂O₃@PPy) as the highly selective and durable electrocatalysts for NRR under ambient conditions. Sulfur doping and PPy coating remarkably improve the charge transfer efficiency of S-Fe₂O₃@PPy, and the interactions between PPy and Fe₂O₃ nanoparticles produce abundant oxygen vacancies as active sites for NRR. This catalyst achieves an NH₃ production rate of 22.1 μg h^-1 mg_cat^-1 and a very-high Faradic efficiency of 24.6%, surpassing other Fe₂O₃ based NRR catalysts. Density functional theory calculations show that the S-coordinated iron site can successfully activate the N₂ molecule and optimize the energy barrier during the reduction process, resulting in a small theoretical limiting potential.

NiMoO4 nanorods with oxygen vacancies self-supported on Ni foam towards high-efficiency electrocatalytic conversion of nitrite to ammonia

As an eco-friendly and sustainable strategy, the electrochemical reduction of nitrite (NO₂^-) can simultaneous generation of NH₃ and treatment of NO₂^- contamination in the environment. Herein, monoclinic NiMoO₄ nanorods with abundant oxygen vacancies self-supported on Ni foam (NiMoO₄/NF) are considered high-performance electrocatalysts for ambient NH₃ synthesis by reduction of NO₂^-, which can deliver an outstanding yield of 18089.39 ± 227.98 μg h^-1 cm^-2 and a preferable FE of 94.49 ± 0.42% at -0.8 V. Additionally, its performance remains relatively stable during long-term operation as well as cycling tests. Furthermore, density functional theory calculations unveil the vital role of oxygen vacancies in promoting nitrite adsorption and activation, ensuring efficient NO₂^-RR towards NH₃. A Zn-NO₂^- battery with NiMoO₄/NF as the cathode shows high battery performance as well.

Oxygen Vacancy Induced Strong Metal-Support Interactions on Ni/Ce0.8Zr0.2O2 Nanorod Catalysts for Promoting Steam Reforming of Toluene: Experimental and Computational Studies

To develop an efficient Ni-based steam reforming catalyst for tar removal from the products of biomass gasification, Ni/Ce_0.8Zr_0.2O₂ nanorods were designed. The Ni/Ce_0.8Zr_0.2O₂ nanorod was used as a catalyst in steam reforming of toluene, which was regarded as a model compound of biomass gasification tar. At gas hourly space velocity (GHSV) of 24,000 h^-1 and Ni loading of 5 wt %, the 5Ni/Ce_0.8Zr_0.2O₂ nanorod catalyst achieved 100% of toluene conversion at 600 °C. After 10 h of operation, toluene conversion still reached 87.6%, and the carbon deposition rate was only 1.9 mg/g_cat h^-1. The experimental results demonstrated that the 5Ni/Ce_0.8Zr_0.2O₂ nanorod catalyst showed much higher catalytic activity and coking resistance than other Ni-based catalysts reported in the literature. Through different characterization technologies and density functional theory calculations, it was confirmed that the excellent catalytic performance was attributed to the strong metal-support interaction (SMSI) between Ni and the {100} facet of Ce_0.8Zr_0.2O₂. The special surface structure of {100} allowed Ni atoms to anchor to the surface oxygen vacancies and maintained its reduced state by electron transport between surface atoms. The anchored Ni facilitated oxygen vacancies formation and H₂O dissociation on the support, while the support modulated the electronic structure of Ni, which promoted its ability to toluene activation.

A Plasmon Resonance Enhanced Photo-Electrode to Promote NH3 Yield in Sustainable N2 Conversion

A key challenge for electrochemical nitrogen reduction reactions (NRR) is the difficulty for conventional catalysts to achieve high currents at low H* coverage to produce appreciable NH₃ . Herein, we specially designed an Au nanoparticle-embedded ZnSe photo-electrode to solve the problem. As-designed photo-electrode achieves excellent NRR performance with a high NH₃ yield (12.2 μg cm^-2 h^-1 ) and Faradaic efficiency (27.3 %). Our work reveals that the unique plasmon resonance effect of embedded Au nanoparticles plays a key role in increasing catalytic current when the H* coverage is decreased. Moreover, we successfully established a correlation between H* coverage and NRR performance based on theoretical calculations and experimental observations. This work paves the path for the future design of catalytic materials to overcome the selectivity and yield challenge of sustainable NH₃ production.

·H effectively enhance electrocatalytic nitrogen fixation

Nowadays, most reported ammonia (NH₃) yields and Faradaic efficiency (FE) of electrocatalysts are very low in the field of electrocatalytic nitrogen reduction reactions (NRR). Here, we are reported ·H for the first time in the field of electrocatalytic NRR, which are generated by sulfite (SO₃^2-) and H₂O in electrolyte solutions upon exposure to UV light. The high NH₃ yields can achieve 100.7 μg h^-1 mg_cat^-1, while stability can achieve 64 h and the FE can achieve 27.1% at -0.3 V (vs. RHE) with UV irradiation. In situ Fourier transform infrared spectroscopy (FTIR), electron spin resonance (ESR), density functional theory (DFT) and ¹H nuclear magnetic resonance (NMR) tests showed that the ∙H effectively lowered the reaction energy barrier at each step of the NRR process and inhibits the occurrence of competitive hydrogen evolution reaction (HER). This explores the path and provides ideas for the field of electrocatalysis involving water.

Universal Synthesized Strategy for Amorphous Pd-Based Nanosheets Boosting Ambient Ammonia Electrosynthesis

The electrocatalytic nitrogen reduction reaction (NRR) is emerging as a great promise for ambient and sustainable NH₃ production while it still suffers from the high adsorption energy of N₂ , the difficulty of *NN protonation, and inevitable hydrogen evolution, leading to a great challenge for efficient NRR. Herein, we synthesized a series of amorphous trimetal Pd-based (PdCoM (M = Cu, Ag, Fe, Mo)) nanosheets (NSs) with an ultrathin 2D structure, which shows high efficiency and robust electrocatalytic nitrogen fixation. Among them, amorphous PdCoCu NSs exhibit excellent NRR activity at low overpotentials with an NH₃ yield of 60.68 µg h^-1 mg_cat ^-1 and a corresponding Faraday efficiency of 42.93% at -0.05 V versus reversible hydrogen electrode as well as outstanding stability with only 5% decrease after a long test period of 40 h at room temperature. The superior NRR activity and robust stability should be attributed to the large specific surface area, abundant active sites as well as structural engineering and electronic effect that boosts up the Pd 4d band center, which further efficiently restrains the hydrogen evolution. This work offers an opportunity for more energy conversion devices through the novel strategy for designing active and stable catalysts.

Microenvironment Regulation of the Ti3C2Tx MXene Surface for Enhanced Electrochemical Nitrogen Reduction

The overwhelmingly competitive hydrogen evolution reaction (HER) is a bottleneck challenge in the electrocatalytic nitrogen reduction reaction (eNRR) process. Herein, we develop a general and effective strategy to suppress the HER via covalent surface functionalization to modulate the local microenvironment of the electrocatalyst. A hydrophobic molecular layer with tunable coverage density was coated on the surface of Ti₃C₂T_x MXene, and the one with appropriate coverage density significantly improved the eNRR efficiency with an excellent faradaic efficiency (FE) of 38.01% at -0.35 V and a high NH₃ yield rate of 17.81 μg h^-1mg_cat^-1 at -0.55 V (vs RHE) in a Na₂SO₄ solution, which were 3.5-fold in FE and 6.5-fold in NH₃ yield rate higher than those of the pristine Ti₃C₂T_x. Experimental results combined with molecular dynamics (MD) simulations reveal that the hydrophobic molecular layer on the surface greatly limits the proton transfer and benefits higher exposure of active sites with enhanced N₂ chemisorption ability, which cumulatively contribute to the boosted eNRR efficiency.

Rigorous Assessment of Cl- -Based Anolytes on Electrochemical Ammonia Synthesis

Many challenges in the electrochemical synthesis of ammonia have been recognized with most effort focused on delineating false positives resulting from unidentified sources of nitrogen. However, the influence of oxidizing anolytes on the crossover and oxidization of ammonium during the electrolysis reaction remains unexplored. Here it is reported that the use of analytes containing halide ions (Cl^- and Br^- ) can rapidly convert the ammonium into N₂ , which further intensifies the crossover of ammonium. Moreover, the extent of migration and oxidation of ammonium is found to be closely associated with external factors, such as applied potentials and the concentration of Cl^- . These findings demonstrate the profound impact of oxidizing anolytes on the electrochemical synthesis of ammonia. Based on these results, many prior reported ammonia yield rates are calibrated. This work emphasizes the significance of avoiding selection of anolytes that can oxidize ammonium, which is believed to promote further progress in electrochemical nitrogen fixation.

In Situ Derived Co2B Nanosheet Array: A High-Efficiency Electrocatalyst for Ambient Ammonia Synthesis via Nitrate Reduction

Ambient ammonia synthesis via electrochemical nitrate (NO3-) reduction is regarded as a green alternative to the Haber-Bosch process. Herein, we report the in situ derivation of an amorphous Co2B layer on a Co3O4 nanosheet array on a Ti mesh (Co2B@Co3O4/TM) for efficient NH3 production via selective electroreduction of NO3- under ambient conditions. In 0.1 M PBS and 0.1 M NaNO3, Co2B@Co3O4/TM exhibits a maximum Faradaic efficiency of 97.0% at -0.70 V and a remarkable NH3 yield of 8.57 mg/h/cm2 at -1.0 V, with durability for stable NO3--to-NH3 conversion over eight recycling tests and 12 h of electrolysis. Additionally, it can be applied as an efficient cathode material for Zn-NO3- batteries to produce NH3 while generating electricity. The catalytic mechanisms on Co2B@Co3O4 are further revealed by theoretical calculations.

Increased Oxygen Vacancies in CeO2 for Improved Electrocatalytic Nitrogen Reduction Performance

Electrochemical nitrogen fixation is a sustainable and economical strategy to produce ammonia. However, fabricating efficient electrocatalysts for nitrogen fixation is still challenging. Theoretical predictions prove that the oxygen vacancy is able to modulate the electronic state of CeO₂ and enhance its electrical conductivity, thus promoting the electrochemical nitrogen reduction reaction (NRR) process. Herein, CeO₂ with high oxygen vacancy concentration was prepared via a two-step pyrolysis strategy of Ce metal-organic frameworks (MOFs, denoted H-CeO₂). Compared to CeO₂ with low oxygen vacancy concentration synthesized via one-step pyrolysis of Ce-MOFs (denoted L-CeO₂), H-CeO₂ exhibits a large NH₃ yield rate (25.64 μg h^-1 mg_cat^-1 at -0.5 V vs reversible hydrogen electrode, RHE) and high faradaic efficiency (FE, 6.3% at -0.4 V vs RHE).

Ni nanoparticle-decorated biomass carbon for efficient electrocatalytic nitrite reduction to ammonia

Electrocatalytic nitrite (NO₂^-) reduction to ammonia (NH₃) can not only synthesize value-added NH₃, but also remove NO₂^- pollutants from the environment. However, the low efficiency of NO₂^--to-NH₃ conversion hinders its applications. Here, Ni nanoparticle-decorated juncus-derived biomass carbon prepared at 800 °C (Ni@JBC-800) serves as an efficient catalyst for NH₃ synthesis by selective electroreduction of NO₂^-. This catalyst shows a remarkable NH₃ yield of 4117.3 μg h^-1 mg_cat.^-1 and a large faradaic efficiency of 83.4% in an alkaline electrolyte. The catalytic mechanism is further investigated by theoretical calculations.

High-Efficiency Ammonia Electrosynthesis on Anatase TiO2-x Nanobelt Arrays with Oxygen Vacancies by Selective Reduction of Nitrite

Electrocatalytic reduction of nitrite to NH₃ provides a new route for the treatment of nitrite in wastewater, as well as an attractive alternative to NH₃ synthesis. Here, we report that an oxygen vacancy-rich TiO_2-x nanoarray with different crystal structures self-supported on the Ti plate can be prepared by hydrothermal synthesis and by subsequently annealing it in an Ar/H₂ atmosphere. Anatase TiO_2-x (A-TiO_2-x) can be a superb catalyst for the efficient conversion of NO₂^- to NH₃; a high NH₃ yield of 12,230.1 ± 406.9 μg h^-1 cm^-2 along with a Faradaic efficiency of 91.1 ± 5.5% can be achieved in a 0.1 M NaOH solution containing 0.1 M NaNO₂ at -0.8 V, which also exhibits preferable durability with almost no decay of catalytic performances after cycling tests and long-term electrolysis. Furthermore, a Zn-NO₂^- battery with such A-TiO_2-x as a cathode delivers a power density of 2.38 mW cm^-2 as well as a NH₃ yield of 885 μg h^-1 cm^-2.

Direct eight-electron NO3−-to-NH3 conversion: using a Co-doped TiO2 nanoribbon array as a high-efficiency electrocatalyst

A Co-TiO2 nanoribbon array supported on a Ti plate is a high-efficiency catalyst for electrochemical NO3–-to-NH3 conversion, capable of attaining a large NH3 yield of 1127 μmol h−1 cm−2 and high Faradaic efficiency of 98.2%.

Amorphous CoB nanoarray as a high-efficiency electrocatalyst for nitrite reduction to ammonia

Amorphous CoB nanoarray is a high-efficiency catalyst for electrocatalytic NO2−-to-NH3 conversion, capable of attaining a large NH3 yield of 233.1 μmol h−1 cm−2 and a high faradaic efficiency of 95.2% at −0.7 V in 0.1 M Na2SO4 with 400 ppm NO2−.

A colorimetric detection strategy and micromotor-assisted photo-Fenton like degradation for hydroquinone based on the peroxidase-like activity of Co3O4–CeO2 nanocages

Co3O4–CeO2 micromotors were fabricated and the colorimetric detection and micromotor-assisted photodegradation capability were studied.