High-Dispersive Pd Nanoparticles on Hierarchical N-Doped Carbon Nanocages to Boost Electrochemical CO2 Reduction to Formate at Low Potential

Electrochemical CO₂ reduction reaction (CO₂RR) to value-added chemicals/fuels is an effective strategy to achieve the carbon neutral. Palladium is the only metal to selectively produce formate via CO₂RR at near-zero potentials. To reduce cost and improve activity, the high-dispersive Pd nanoparticles on hierarchical N-doped carbon nanocages (Pd/hNCNCs) are constructed by regulating pH in microwave-assisted ethylene glycol reduction. The optimal catalyst exhibits high formate Faradaic efficiency of >95% within −0.05–0.30 V and delivers an ultrahigh formate partial current density of 10.3 mA cm⁻² at the low potential of −0.25 V. The high performance of Pd/hNCNCs is attributed to the small size of uniform Pd nanoparticles, the optimized intermediates adsorption/desorption on modified Pd by N-doped support, and the promoted mass/charge transfer kinetics arising from the hierarchical structure of hNCNCs. This study sheds light on the rational design of high-efficient electrocatalysts for advanced energy conversion.     

Regulating the Electronic Structure of Bismuth Nanosheets by Titanium Doping to Boost CO2 Electroreduction and Zn–CO2 Batteries

The electrochemical carbon dioxide reduction reaction (E-CO₂RR) to formate is a promising strategy for mitigating greenhouse gas emissions and addressing the global energy crisis. Developing low-cost and environmentally friendly electrocatalysts with high selectivity and industrial current densities for formate production is an ideal but challenging goal in the field of electrocatalysis. Herein, novel titanium-doped bismuth nanosheets (Ti Bi NSs) with enhanced E-CO₂RR performance are synthesized through one-step electrochemical reduction of bismuth titanate (Bi₄Ti₃O₁₂). We comprehensively evaluated Ti Bi NSs using in situ Raman spectra, finite element method, and density functional theory. The results indicate that the ultrathin nanosheet structure of Ti Bi NSs can accelerate mass transfer, while the electron-rich properties can accelerate the production of *CO₂⁻ and enhance the adsorption strength of *OCHO intermediate. The Ti Bi NSs deliver a high formate Faradaic efficiency (FE_formate) of 96.3% and a formate production rate of 4032 µmol h⁻¹ cm⁻² at −1.01 V versus RHE. An ultra-high current density of −338.3 mA cm⁻² is achieved at −1.25 versus RHE, and simultaneously FE_formate still reaches more than 90%. Furthermore, the rechargeable Zn–CO₂ battery using Ti Bi NSs as a cathode catalyst achieves a maximum power density of 1.05 mW cm⁻² and excellent charging/discharging stability of 27 h.     

Sn-Ag Synergistic Effect Enhances High-Rate Electrocatalytic CO2-to-Formate Conversion on Porous Poly(Ionic Liquid) Support

The electrocatalytic transformation of carbon dioxide (CO₂) to formate is a promising route for highly efficient conversion and utilization of CO₂ gas, due to the low production cost and the ease of storage of formate. In this work, porous poly(ionic liquid) (PPIL)-based tin-silver (Sn-Ag) bimetallic hybrids (PPIL^m-Sn_xAg_10-x) are prepared for high-performance formate electrolytic generation. Under optimal conditions, an excellent formate Faradaic efficiency of 95.5% with a high partial current density of 214.9 mA cm⁻² is obtained at −1.03 V (vs reversible hydrogen electrode). Meanwhile, the high selectivity of formate (>≈83%) is maintained in a wide potential range (>630 mV). Mechanistic studies demonstrate that the presence of Ag-species is vital for the formation, maintenance, and high dispersion of tetravalent Sn(IV)-species, which accounts for the active sites for CO₂-to-formate conversion. Further, the introduction of Ag-species significantly enhances the activity by increasing the electron density near the Fermi energy level.     

Selective CO2 Electroreduction to Formate on Polypyrrole-Modified Oxygen Vacancy-Rich Bi2O3 Nanosheet Precatalysts by Local Microenvironment Modulation

Challenges remain in the development of highly efficient catalysts for selective electrochemical transformation of carbon dioxide (CO₂) to high-valued hydrocarbons. In this study, oxygen vacancy-rich Bi₂O₃ nanosheets coated with polypyrrole (Bi₂O₃@PPy NSs) are designed and synthesized, as precatalysts for selective electrocatalytic CO₂reduction to formate. Systematic material characterization demonstrated that Bi₂O₃@PPy precatalyst can evolve intoBi₂O₂CO₃@PPy nanosheets with rich oxygen vacancies (Bi₂O₂CO₃@PPy NSs) via electrolyte-mediated conversion and function as the real active catalyst for CO₂ reduction reaction electrocatalysis. Coating catalyst with a PPy shell can modulate the interfacial microenvironment of active sites, which work in coordination with rich oxygen vacancies in Bi₂O₂CO₃ and efficiently mediate directional selective CO₂ reduction toward formate formation. With the fine-tuning of interfacial microenvironment, the optimized Bi₂O₃@PPy-2 NSs derived Bi₂O₂CO₃@PPy-2 NSs exhibit a maximum Faradaic efficiency of 95.8% at −0.8 V (versus. reversible hydrogen electrode) for formate production. This work might shed some light on designing advanced catalysts toward selective electrocatalytic CO₂ reduction through local microenvironment engineering.     

Interface-Induced Electrocatalytic Enhancement of CO2-to-Formate Conversion on Heterostructured Bismuth-Based Catalysts

Electrochemical CO₂ reduction reaction (CO₂RR) is a promising approach to convert CO₂ to carbon-neutral fuels using external electric powers. Here, the Bi₂S₃-Bi₂O₃ nanosheets possessing substantial interface being exposed between the connection of Bi₂S₃ and Bi₂O₃ are prepared and subsequently demonstrate to improve CO₂RR performance. The electrocatalyst shows formate Faradaic efficiency (FE) of over 90% in a wide potential window. A high partial current density of about 200 mA cm^?2 at ?1.1 V and an ultralow onset potential with formate FE of 90% are achieved in a flow cell. The excellent electrocatalytic activity is attributed to the fast-interfacial charge transfer induced by the electronic interaction at the interface, the increased number of active sites, and the improved CO₂ adsorption ability. These collectively contribute to the faster reaction kinetics and improved selectivity and consequently, guarantee the superb CO₂RR performance. This study provides an appealing strategy for the rational design of electrocatalysts to enhance catalytic performance by improving the charge transfer ability through constructing a functional heterostructure, which enables interface engineering toward more efficient CO₂RR.     

InBi Bimetallic Sites for Efficient Electrochemical Reduction of CO2 to HCOOH

Formic acid is receiving intensive attention as being one of the most progressive chemical fuels for the electrochemical reduction of carbon dioxide. However, the majority of catalysts suffer from low current density and Faraday efficiency. To this end, an efficient catalyst of In/Bi-750 with InO_x nanodots load is prepared on a two-dimensional nanoflake Bi₂O₂CO₃ substrate, which increases the adsorption of ^*CO₂ due to the synergistic interaction between the bimetals and the exposure of sufficient active sites. In the H-type electrolytic cell, the formate Faraday efficiency (FE) reaches 97.17% at –1.0 V (vs reversible hydrogen electrode (RHE)) with no significant decay over 48 h. A formate Faraday efficiency of 90.83% is also obtained in the flow cell at a higher current density of 200 mA cm⁻². Both in-situ Fourier transform infrared spectroscopy (FT-IR) and theoretical calculations show that the BiIn bimetallic site can deliver superior binding energy to the ^*OCHO intermediate, thereby fundamentally accelerating the conversion of CO₂ to HCOOH. Furthermore, assembled Zn-CO₂ cell exhibits a maximum power of 6.97 mW cm⁻¹ and a stability of 60 h.     

Anion Exchange Facilitates the In Situ Construction of Bi/Bi?O Interfaces for Enhanced Electrochemical CO2-to-Formate Conversion Over a Wide Potential Window

Electrochemical reduction of CO₂ (CO₂RR) into value-added products is a promising strategy to reduce energy consumption and solve environmental issues. Formic acid/formate is one of the high-value, easy-to-collect, and economically viable products. Herein, the reconstructed Bi₂O₂CO₃ nanosheets (BOC_R NSs) are synthesized by an in situ electrochemical anion exchange strategy from Bi₂O₂SO₄ as a pre-catalyst. The BOC_R NSs achieve a high formate Faradaic efficiency (FE_formate) of 95.7% at −1.1 V versus reversible hydrogen electrode (vs. RHE), and maintain FE_formate above 90% in a wide potential range from −0.8 to −1.5 V in H-cell. The in situ spectroscopic studies reveal that the obtained BOC_R NSs undergo the anion exchange from Bi₂O₂SO₄ to Bi₂O₂CO₃ and further promote the self-reduction to metallic Bi to construct Bi/Bi O active site to facilitate the formation of OCHO^* intermediate. This result demonstrates anion exchange strategy can be used to rational design high performance of the catalysts toward CO₂RR.     

Geometric and Electronic Structural Engineering of Isolated Ni Single Atoms for a Highly Efficient CO2 Electroreduction

Tuning the coordination environment and geometric structures of single atom catalysts is an effective approach for regulating the reaction mechanism and maximize the catalytic efficiency of single-atom centers. Here, a template-based synthesis strategy is proposed for the synthesis of high-density NiN_x sites anchored on the surface of hierarchically porous nitrogen-doped carbon nanofibers (Ni-HPNCFs) with different coordination environments. First-principles calculations and advanced characterization techniques demonstrate that the single Ni atom is strongly coordinated with both pyrrolic and pyridinic N dopants, and that the predominant sites are stabilized by NiN₃ sites. This dual engineering strategy increases the number of active sites and utilization efficiency of each single atom as well as boosts the intrinsic activity of each active site on a single-atom scale. Notably, the Ni-HPNCF catalyst achieves a high CO Faradaic efficiency (FE_CO) of 97% at a potential of −0.7 V, a high CO partial current density (j_CO) of 49.6 mA cm⁻² (−1.0 V), and a remarkable turnover frequency of 24 900 h⁻¹ (−1.0 V) for CO₂ reduction reactions (CO₂RR). Density functional theory calculations show that compared to pyridinic-type NiN_x, the pyrrolic-type NiN₃ moieties display a superior CO₂RR activity over hydrogen evolution reactions, resulting in their superior catalytic activity and selectivity.     

Regulated Surface Electronic States of CuNi Nanoparticles through Metal-Support Interaction for Enhanced Electrocatalytic CO2 Reduction to Ethanol

Developing stable catalysts with higher selectivity and activity within a wide potential range is critical for efficiently converting CO₂ to ethanol. Here, the carbon-encapsulated CuNi nanoparticles anchored on nitrogen-doped nanoporous graphene (CuNi@C/N-npG) composite are designedly prepared and display the excellent CO₂ reduction performance with the higher ethanol Faradaic effiency (FE_ethanol ≥ 60%) in a wide potential window (600 mV). The optimal cathodic energy efficiency (47.6%), Faradaic efficiency (84%), and selectivity (96.6%) are also obtained at −0.78 V versus reversible hydrogen electrode (RHE). Combining with the density functional theory (DFT) calculations, it is demonstrated that the stronger metal-support interaction (Ni-N-C) can regulate the surface electronic structure effectively, boosting the electron transfer and stabilizing the active sites (Cu⁰-Cu^δ+) on the surface of CuNi@C/N-npG, finally realizing the controllable transition of reaction intermediates. This work may guide the designs of electrocatalysts with highly catalytic performance for CO₂ reduction to C₂₊ products.     

Integrated 3D Open Network of Interconnected Bismuthene Arrays for Energy-Efficient and Electrosynthesis-Assisted Electrocatalytic CO2 Reduction

Electrocatalytic CO₂ reduction reaction (CO₂RR) toward formate production can be operated under mild conditions with high energy conversion efficiency while migrating the greenhouse effect. Herein, an integrated 3D open network of interconnected bismuthene arrays (3D Bi-ene-A/CM) is fabricated via in situ electrochemically topotactic transformation from BiOCOOH nanosheet arrays supported on the copper mesh. The resulted 3D Bi-ene-A/CM consists of 2D atomically thin metallic bismuthene (Bi-ene) in the form of an integrated array superstructure with a 3D interconnected and open network, which harvests the multiple structural advantages of both metallenes and self-supported electrodes for electrocatalysis. Such distinctive superstructure affords the maximized quantity and availability of the active sites with high intrinsic activity and superior charge and mass transfer capability, endowing the catalyst with good CO₂RR performance for stable formate production with high Faradaic efficiency (≈90%) and current density (>300 mA cm^?2). Theoretical calculation verifies the superior intermediate stabilization of the dominant Bi plane during CO₂RR. Moreover, by further coupling anodic methanol oxidation reaction, an exotic electrolytic system enables highly energy-efficient and value-added pair-electrosynthesis for concurrent formate production at both electrodes, achieving substantially improved electrochemical and economic efficiency and revealing the feasibility for practical implementation.     

Revealing the Kinetic Balance between Proton-Feeding and Hydrogenation in CO2 Electroreduction

Electrocatalytic reduction of CO₂ to high-value-added chemicals provides a feasible path for global carbon balance. Herein, the fabrication of Ni_NPx@Ni_SAy-NG (x,y = 1, 2, 3; NG = nitrogen-doped graphite) is reported, in which Ni single atom sites (Ni_SA) and Ni nanoparticles (Ni_NP) coexist. These Ni_NPx@Ni_SAy-NG presented a volcano-like trend for maximum CO Faradaic efficiency (FE_CO) with the highest point at Ni_NP2@Ni_SA2-NG in CO₂RR. Ni_NP2@Ni_SA2-NG exhibited ≈98% of maximum FE_CO and a large current density of −264 mA cm⁻² at −0.98 V (vs. RHE) in the flow cell. In situ experiment and density functional theory (DFT) calculations confirmed that the proper content of Ni_SA and Ni_NP balanced kinetic between proton-feeding and CO₂ hydrogenation. The Ni_NP in Ni_NP2@Ni_SA2-NG promoted the formation of H* and reduced the energy barrier of *CO₂ hydrogenation to *COOH, and CO desorption can be efficiently facilitated by Ni_SA sites, thereby resulting in enhanced CO₂RR performance.     

Selective and Stable CO2 Electroreduction to CH4 via Electronic Metal–Support Interaction upon Decomposition/Redeposition of MOF

The CO₂ electroreduction to fuels is a feasible approach to provide renewable energy sources. Therefore, it is necessary to conduct experimental and theoretical investigations on various catalyst design strategies, such as electronic metal–support interaction, to improve the catalytic selectivity. Here a solvent-free synthesis method is reported to prepare a copper (Cu)-based metal–organic framework (MOF) as the precursor. Upon electrochemical CO₂ reduction in aqueous electrolyte, it undergoes in situ decomposition/redeposition processes to form abundant interfaces between Cu nanoparticles and amorphous carbon supports. This Cu/C catalyst favors the selective and stable production of CH₄ with a Faradaic efficiency of ≈55% at −1.4 V versus reversible hydrogen electrode (RHE) for 12.5 h. The density functional theory calculation reveals the crucial role of interfacial sites between Cu and amorphous carbon support in stabilizing the key intermediates for CO₂ reduction to CH₄. The adsorption of COOH* and CHO* at the Cu/C interface is up to 0.86 eV stronger than that on Cu(111), thus promoting the formation of CH₄. Therefore, it is envisioned that the strategy of regulating electronic metal–support interaction can improve the selectivity and stability of catalyst toward a specific product upon electrochemical CO₂ reduction.     

Defective TiO2−x for High-Performance Electrocatalytic NO Reduction toward Ambient NH3 Production

Synthesis of green ammonia (NH₃) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton-involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen-defective TiO₂ nanoarray supported on Ti plate (TiO_2−x/TP) behaves as an efficient catalyst for NO reduction to NH₃. In 0.2 m phosphate-buffered electrolyte, such TiO_2−x/TP shows competitive electrocatalytic NH₃ synthesis activity with a maximum NH₃ yield of 1233.2 µg h⁻¹ cm⁻² and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO_2−x (101) compared to perfect TiO₂ (101). And the low energy barrier of 0.7 eV on TiO_2−x (101) for the potential-determining step further highlights the greatly improved intrinsic activity. In addition, a Zn-NO battery is fabricated with TiO_2−x/TP and Zn plate to obtain an NH₃ yield of 241.7 µg h⁻¹ cm⁻² while providing a peak power density of 0.84 mW cm⁻².     

Effects of Europium Substitution on the Microstructure and Electric Properties of Bismuth Ferrite Ceramics

Bi_1−x Eu _x FeO₃ (x=0.00–0.15) ceramics were synthesized by solid state reaction method with rapid liquid phase sintering process at different europium content and the microstructure and electrical properties of the samples were investigated. X-ray diffraction (XRD) studies show that europium substitution has changed the structure of BiFeO₃ from rhombohedral R3c to orthorhombic Pnma and decreased the impurity phase. Raman spectra results also conform that a structure transition occurs at about x=0.20, and indicate that the Eu substitution at Bi site can obviously affect the Bi–O bond. Impedance analyzer measurements show that both dielectric constant and dielectric loss are strongly dependent on the Eu content. The dielectric constant of the Bi_1−x Eu _x FeO₃ increases with increasing Eu content from 0.00 to 0.20, then decreases with increasing Eu content from 0.20 to 0.30. The dielectric constant measured at 100 Hz is 542.0 for the x=0.20 sample, which is about 8.5 times as big as that for unsubsitituted BiFeO₃. The dielectric loss can be effectively decreased by the substitution of Eu for Bi. In addition, the leakage current measurements show that the substitution of Eu can effectively reduce the leakage current density of BiFeO₃.     

The Effect of Mn Substitution on Properties of Bi1.6Pb0.4Sr2Ca2?x Mn x Cu3O y Superconductors

The effects of Mn substitution on the physical properties and structural characteristics of Bi_1.6Pb_0.4Sr₂Ca₂Cu_3−x Mn _x Oy (Bi-2223) superconductor system have been studied. For this, the samples of nominal composition Bi_1.6Pb_0.4Sr₂Ca₂Cu_3−x Mn _x Oy (x=0.00, 0.10, 0.15 & 0.20) was prepared by the solid-state reaction method. It has been found that the effects of Mn substitution favor the formation of Bi-2223 phases. The phase identification/gross structural characteristics of synthesized (HTSC) materials explored through powder X-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters (a=5.4918 ?, b=5.4071 ?, and c=37.0608 ?) up to Mn concentration of x=0.20. The critical transition temperature (T _c) measured by standard four probe method has been found to depress from 108 K to 70 K and transport current density (J _c) has been increased from 4.67×10² to 3.52×10³ A cm⁻² as Mn content (x) increases from 0.00 to 0.20. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM and AFM) results that voids and grains size increases as the Mn concentration increases besides the nanosphere like structures on the surface of the Mn doped Bi-2223 sample.     

A comparative study of different solvothermal methods for the synthesis of Sn<Superscript>2+</Superscript>-doped BaTiO<Subscript>3</Subscript> powders and their dielectric properties

Ternary oxides containing Sn²⁺ are rare and difficult to prepare by the conventional solid state reactions due to the disproportionation of Sn²⁺ to Sn⁴⁺ and Sn at high temperatures. In this article, Sn²⁺-doped barium titanate, Ba_1−x Sn _x TiO₃ (x = 0.00, 0.02, 0.05, and 0.10) nanopowders were successfully synthesized at a moderate temperature by a microwave-assisted solvothermal reaction (MSR) and a solvothermal reaction with rolling (SRR). The powders obtained using the MSR and SRR consisted of nanoparticles of 20–50 nm and 100–120 nm in diameter, respectively. The dielectric constant of the sample increased by doping with a small amount of Sn²⁺ (x ≤ 0.05), but decreased by doping in excess amounts of it.     

Structural and Transport Properties of Sn-Doped Bi2Te3 – x Se x Single Crystals

The transport properties of Bi_{2 – y} Sn _y Te_{3 – x} Se _x solid solutions are studied. The results demonstrate that doping with Sn has a strong effect on the temperature dependences of the thermoelectric power and electrical conductivity of the crystals. This suggests that the valence band of the crystals contains Sn-related resonance states. The point defects and dislocation system in Bi₂Te₃ and Bi_{2 – y} Sn _y Te_{3 – x} Se _x solid solutions are studied by transmission electron microscopy. It is shown that the predominant defects in the crystals studied, grown by the Czochralski technique, are dislocations lying in the (0001) plane. The estimated dislocation density is 10⁸ to 10⁹ cm^–2, and the primary slip plane is (0001). Electron-microscopic examination indicates the presence of stacking faults and very small dislocation loops in both Bi₂Te₃ and Bi_{2 – y} Sn _y Te_{3 – x} Se _x single crystals. Since all of the crystals are highly degenerate semiconductors, it is reasonable to assume that structural defects have an insignificant effect on their electrical properties.     

Enhanced the Efficiency of Electrocatalytic CO2-to-CO Conversion by Cd Species Anchored into Metal-Organic Framework

Metal-organic frameworks (MOFs) as a promising platform for electrocatalytic CO₂ conversion are still restricted by the low efficiency or unsatisfied selectivity for desired products. Herein, zirconium-based porphyrinic MOF hollow nanotubes with Cd sites (Cd-PCN-222HTs) are reported for electrocatalytic CO₂-to-CO conversion. The dispersed Cd species are anchored in PCN-222HTs and coordinated by N atoms of porphyrin structures. It is discovered that Cd-PCN-222HTs have glorious electrocatalytic activity for selective CO production in ionic liquid-water (H₂O)-acetonitrile (MeCN) electrolyte. The CO Faradaic efficiency (FE_CO) of >80% could be maintained in a wide potential range from −2.0 to −2.4 V versus Ag/Ag⁺, and the maximum current density could reach 68.0 mA cm⁻² at −2.4 V versus Ag/Ag⁺ with a satisfied turnover frequency of 26 220 h⁻¹. The enhanced efficiency of electrocatalytic CO₂ conversion of Cd-PCN-222HTs is closely related to its hollow structure, anchored Cd species, and good synergistic effect with electrolyte. The density functional theory calculations indicate that the dispersed Cd sites anchored in PCN-222HTs not only favor the formation of *COOH intermediate but also hinder the hydrogen evolution reaction, resulting in high activity of electrocatalytic CO₂-to-CO conversion.     

Nanoscale Janus Z-Scheme Heterojunction for Boosting Artificial Photosynthesis

Artificial photosynthesis for CO₂ reduction coupled with water oxidation currently suffers from low efficiency due to inadequate interfacial charge separation of conventional Z-scheme heterojunctions. Herein, an unprecedented nanoscale Janus Z-scheme heterojunction of CsPbBr₃/TiO_x is constructed for photocatalytic CO₂ reduction. Benefitting from the short carrier transport distance and direct contact interface, CsPbBr₃/TiO_x exhibits significantly accelerated interfacial charge transfer between CsPbBr₃ and TiO_x (8.90 × 10⁸ s⁻¹) compared with CsPbBr₃:TiO_x counterpart (4.87 × 10⁷ s−¹) prepared by traditional electrostatic self-assembling. The electron consumption rate of cobalt doped CsPbBr₃/TiO_x can reach as high as 405.2 ± 5.6 µmol g⁻¹ h⁻¹ for photocatalytic CO₂ reduction to CO coupled with H₂O oxidation to O₂ under AM1.5 sunlight (100 mW cm⁻²), over 11-fold higher than that of CsPbBr₃:TiO_x, and surpassing the reported halide-perovskite-based photocatalysts under similar conditions. This work provides a novel strategy to boost charge transfer of photocatalysts for enhancing the performance of artificial photosynthesis.     

Engineering Under-Coordinated Active Sites with Tailored Chemical Microenvironments over Mosaic Bismuth Nanosheets for Selective CO2 Electroreduction to Formate

Selective electrochemical reduction of CO₂ into fuels or chemical feedstocks is a promising avenue to achieve carbon-neutral goal, but its development is severely limited by the lack of highly efficient electrocatalysts. Herein, cation-exchange strategy is combined with electrochemical self-reconstruction strategy to successfully develop diethylenetriamine-functionalized mosaic Bi nanosheets (mBi-DETA NSs) for selective electrocatalytic CO₂ reduction to formate, delivering a superior formate Faradaic efficiency of 96.87% at a low potential of −0.8 V_RHE. Mosaic nanosheet morphology of Bi can sufficiently expose the under-coordinated Bi active sites and promote the activation of CO₂ molecules to form the OCHO⁻* intermediate. Moreover, in situ attenuated total reflectance infrared spectra further corroborate that surface chemical microenvironment modulation of mosaic Bi nanosheets via DETA functionalization can improve CO₂ adsorption on the catalyst surface and stabilize the key intermediate (OCHO⁻*) due to the presence of amine groups, thus facilitate the CO₂-to-HCOO⁻ reaction kinetics and promote formate formation.