abstract:Functional carbon-based materials have become a key research direction in the field of advanced electrocatalysis due to their unique structure and properties. Various strategies have been proposed to design and synthesize high-performance carbon-based electrocatalysts. In this review, we comprehensively summarize the latest developments in carbon-based materials for advanced electrocatalysis, with particular emphasis on the structure design strategies and the intrinsic relationship between structure, activity, and performance. The functionalization of multi-dimensional carbon-based materials with enhanced electrocatalytic performance is first addressed. Next, the impact of electronic and structural engineering on the performance of carbon-based materials for electrocatalysis is discussed in terms of the advantages of different types of carbon-based materials in electrocatalytic applications. Finally, the prospects in areas such as precise tuning of functional carbon-based materials, the development of renewable carbon materials, the use of advanced characterization techniques and the promotion of smart manufacturing and responsiveness are highlighted.

The industrial implementation of Solar-driven photocatalysis is hampered by inefficient charge separation, poor reusability and hard retrieval of powdery catalysts. To conquer these drawbacks, a self- floating S-scheme Bi₄O₅Br₂/P-doped C₃N₄/carbon fiber cloth (BB/PN/CC) composed of carbon fibers (CC) as the core and Bi₄O₅Br₂/P-doped C₃N₄ (BB/PN) nanosheets as the shell was constructed as a competent, recyclable cloth-shaped photocatalyst for safe and efficient degradation of aquacultural antibiotics. The BB/PN/CC fabric achieves an exceptional tetracycline degradation rate constant of 0.0118 min^‒1, surpassing CN/CC (0.0015 min^‒1), BB/CC (0.0066 min^‒1) and PN/CC (0.0023 min^‒1) by 6.9, 0.8 and 4.1 folds, respectively. Beyond its catalytic prowess, the photocatalyst’s practical superiority is evident in its effortless recovery and environmental adaptability. The superior catalytic effectiveness stems from the S-scheme configuration, which retains the maximum redox capacities of the constituent BB and PN while enabling efficient spatial detachment of photo-carriers. X-ray photoelectron spectroscopy (XPS), in-situ XPS, and electron paramagnetic resonance analyses corroborate the S-scheme mechanism, revealing electron accumulation on PN and hole retention on BB under illumination. Density functional theory calculations further confirm S-scheme interfacial charge redistribution and internal electric field formation. This study advances the design of macroscopic S-scheme heterojunction photocatalysts for sustainable water purification.

Antibiotics and heavy metals usually co-exist in wastewater and pose serious environmental hazards. Herein, a series of V_Mo-BMO/O_v-BOB S-scheme heterojunctions with double vacancy (Mo vacancy and photoexcited O vacancy) were constructed via an electrostatic assembly method. The removal efficiency of Cr (VI) and tetracycline (TC) over V_Mo-BMO/O_v-BOB-0.3 was 2.47 and 1.13 times than that of a single system, respectively. In-situ EPR demonstrated that the surface O vacancies could be generated under LED light irradiation. These photoexcited O vacancies (P-O_v) enabled V_Mo-BMO/O_v-BOB composites still exhibit satisfactory activity after five successive cycles and an amplified Fermi level gap. The enhancement could be attributed to the enhanced internal electric field and double-vacancy-induced polarization. Additionally, the density functional theory calculation results suggested that double vacancy induced polarization electric field increases the dipole moment, which was conducive to rapid electron transport. Photoluminescence and time-resolved photoluminescence analysis demonstrated that the introduction of S-scheme heterojunction and double vacancy promoted charge transfer and prolonged the lifetime of carriers. Degradation intermediates and toxicity of products were evaluated. In conclusion, a possible mechanism based on V_Mo-BMO/O_v-BOB S-scheme heterojunction in the simultaneous removal of Cr (VI) and TC was proposed.

Harnessing photocatalyzed hydrogen atom transfer (HAT) for the precise activation of C-H/O-H bonds is a pivotal yet challenging strategy to selectively drive oxidative C-C bond scission in renewable lignin, yielding value-added chemicals with exceptional selectivity. Herein, we present a metal-free photochemical strategy that enables selective C-C bond scission in lignin via a unique synergistic HAT pathway driven by triplet-excited 2-ethylanthraquinone (EAQ*) and hydroxyl radicals (^•OH) generated in situ from EAQH₂ and O₂. Under simulated natural conditions, this process achieves a benzaldehyde yield of 146.6 mol% from a lignin-derived phenolic dimer. Mechanistic investigations reveal that preferential activation of the C_α-OH in lignin facilitates a tandem HAT process, forming alkoxy radical intermediates that undergo β-scission to produce benzaldehyde, as corroborated by extensive control reactions and density functional theory calculations. Furthermore, this straightforward protocol efficiently cleaves the C-C bonds of technical kraft lignins, providing a rapid, scalable, and metal-free protocol for lignin valorization under mild conditions.

Single-atom catalysts are promising for H₂O₂ photosynthesis from O₂ and H₂O, but their efficiency is still limited by the ill-defined electronic structure. In this study, Co single-atoms with unique four planar N-coordination and one axial P-coordination (Co-N₄P₁) are decorated on the lateral edges of nanorod-like crystalline g-C₃N₄ (CCN) photocatalysts. Significantly, the electronic structures of central Co as active sites for O₂ reduction reaction (ORR) and planar N-coordinator as active sites for H₂O oxidation reaction (WOR) in Co-N₄P₁ can be well regulated by the synergetic effects of introducing axial P-coordinator, in contrast to the decorated Co single-atoms with only four planar N-coordination (Co-N₄). Specifically, directional photoelectron accumulation at central Co active sites, induced by an introduced midgap level in Co-N₄P₁, mediates the ORR active sites from 4e^--ORR-selective terminal -NH₂ sites to 2e^--ORR-selective Co sites, moreover, an elevated d-band center of Co 3d orbital strengthens ORR intermediate *OOH adsorption, thus jointly facilitating a highly selective and active 2e^--ORR pathway to H₂O₂ photosynthesis. Simultaneously, a downshifted p-band center of N 2p orbital in Co-N₄P₁ weakens WOR intermediate *OH adsorption, thus enabling a preferable 2e^--WOR pathway toward H₂O₂ photosynthesis. Subsequently, Co-N₄P₁ exhibits exceptional H₂O₂ photosynthesis efficiency, reaching 295.6 μmol g^-1 h^-1 with a remarkable solar-to-chemical conversion efficiency of 0.32 %, which is 15 times that of Co-N₄ (19.2 μmol g^-1 h^-1) and 10 times higher than CCN (27.6 μmol g^-1 h^-1). This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H₂O₂ photosynthesis.

The photocatalytic oxidation of methane to methanol using molecule oxygen directly is an attractive catalytic reaction, but designing catalysts to avoid over-oxidation remains a significant challenge. Herein, Cu single-atom anchored on the defective carbon nitride structure (Cu SA/Def-CN) is designed for selective photocatalytic oxidation of methane into methanol using O₂ under mild conditions. The Cu SA/Def-CN catalyst exhibits a high methanol selectivity of 92.8% under optimized conditions. Mechanistic studies reveal a synergistic effect between Def-CN and Cu SA, where Def-CN is responsible for the in-situ generation of hydrogen peroxide, which is subsequently decomposed by the Cu SA sites to produce ·OH radicals that play a key role in the rate-determining step of methane activation to form methanol. Additionally, the presence of Cu SA not only enhances the electron-hole separation efficiency and improves the transfer of the photo-generated charges, but also increases the number of active sites for methane adsorption and activation. These insights provide valuable guidance for designing efficient catalysts for the highly selective photocatalytic oxidation of methane to methanol.

The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates (H_ad) to form strong S-H_ad bonds, resulting in a low photocatalytic H₂ evolution activity. Herein, a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H₂ evolution. To this end, Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO₂ surface by a facile photosynthesis strategy. It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS, thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)- sites. The electron-enriched S^(2+δ)- sites could interact with H_ad via an increased antibonding orbital occupancy, which weakens S-H_ad bonds for efficient H_ad adsorption and desorption, endowing the NiCoS cocatalysts with a highly active H₂ evolution process. Consequently, the optimized NiCoS/TiO₂(1:2) photocatalyst displays the highest H₂ production performance, outperforming the NiS/TiO₂ and CoS/TiO₂ samples by factors of 2.1 and 2.5, respectively. This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.

Photoinduced molecular oxygen activation is crucial for artificial photosynthesis. However, metal-free semiconductor photocatalysts with high activation efficiency are still lacking up to now. Herein, two isomorphic tris(triazolo)triazine-based covalent organic frameworks were successfully constructed under solvothermal conditions. And they possess high crystallinity, inherent porosity with large surface area and good stability. Strong electron donor-acceptor skeletons expand the visible light harvesting, also facilitate the charge separation and thus lead to their superior activity of photoinduced molecular oxygen activation including photosynthesis of tetrahydroquinolines and hydrogen peroxide. This work provides a way to improve the efficiency of molecular oxygen activation through the rational design of COFs, and also opens new avenues for the construction of highly active and metal-free photocatalysts toward sustainable solar-to-chemical energy conversion.

Tetracycline hydrochloride (TCH) exists in various forms in aqueous solution due to pH changes, which not only alters the reactivity of TCH, but also affects the process of reactive oxygen species (ROS) attacking the molecule. Therefore, the rational design of piezo-photocatalytic materials coupled with a comprehensive understanding of the degradation mechanisms of various TCH species constitutes a critical approach to addressing tetracycline antibiotic contamination. In the design and preparation of piezo-photocatalysts, controlling the oxygen vacancy concentration is crucial as it governs the coupling efficiency between piezoelectric response and photocatalytic activity, as well as the strength of spontaneous polarization. Meanwhile, the morphology of the material is a key factor influencing the migration pathways of charge carriers. In this work, hollow spherical Bi4Ti3O12 was synthesized using an inorganic titanium source, demonstrating exceptional piezo-photocatalytic activity. The degradation rate was 1.57 and 5.29 times higher than that of traditional spherical and plate-like morphologies, with a rate constant of k = 0.127. In an innovative approach, density functional theory calculations of local softness and hyper-softness were employed to analyze the reactivity changes of TCH in its different deprotonated states toward reactive oxygen species. Combined with molecular electronegativity analysis, the factors influencing the degradation efficiency were identified. This study provides a solid foundation for developing efficient and environmentally friendly piezo-photocatalysts and offers new insights into the degradation mechanism of TCH.

Neutral oxygen evolution reaction (OER) is a crucial half-reaction for electrocatalytic chemical production under mild condition, but with limited development due to low activity and poor stability. Herein, a tungsten-doped cobalt molybdate (WDCMO) catalyst was synthesized for efficient and durable OER under neutral electrolyte. It is demonstrated that catalyst reconstruction is suppressed by W doping, which stabilizes the Co-O-Mo point-to-point connection in CoMoO₄ architecture and stimulates to a lower valence state of active sites over the surface phase. Thereby, the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER. Meanwhile, the WDCMO catalyst promotes charge transfer and optimizes *OH intermediate adsorption, which improves reaction kinetics and intrinsic activity. Consequently, the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^-2 in neutral electrolyte with an improvement of 182 mV compared with CoMoO₄ electrode. Furthermore, W doping significantly improves the electrode stability from 50 h to more than 320 h, with a suppressive potential attenuation from 2.82 to 0.29 mV h^-1. This work will shed new light on designing rational electrocatalysts for neutral OER.

Plastics are ubiquitous in human life and pose certain hazards to the environment and human body. The increasing amount of CO2 in the atmosphere will lead to the greenhouse effect. Therefore, it is urgent to treat microplastic waste and CO2 by using environmentally friendly and efficient technologies. In this work, we developed an efficient photoelectrocatalytic system composed of Ni single atoms (Ni SAs) supported by P, N-doped amorphous NiFe2O4 (Ni SAs/A-P-N-NFO) as anode and Ag nanoparticles (Ag NPs) supported by CuO/Cu2O nanocubes (Ag NPs@CuO/Cu2O NCs) as cathode for microplastic oxidation and CO2 reduction. The Ni SAs/A-P-N-NFO was synthesized by calcination-H2 reduction method, and it achieved a Faraday efficiency of 93% for the oxidation reaction of poly (ethylene terephthalate) (PET) solution under AM 1.5 G light. As a photocathode, the synthesized Ag NPs@CuO/Cu2O NCs was utilized to reduce CO2 to ethylene and CO at 1.5 V vs. RHE with selectivity of 42% and 55%, respectively. This work shows that the photoelectrocatalysis, as an environmentally friendly technology, is a feasible strategy for reducing the environmental and biological hazards of light plastics, as well as for efficient CO2 reduction.

The catalyst cost is a key factor limiting the CO purification of sintering flue gas. Here, an ultra-low-loading high-entropy catalyst was prepared by simple calcination process. By anchoring multiple active metal sites in the stable anatase TiO₂ phase, it shows efficient CO catalytic oxidation activity. The metal components (Pt, Mn, Fe, Co, Ni) were uniformly dispersed on the surface of TiO₂ in the form of high-entropy compounds and undergo strong metal and support interaction with TiO₂. The results showed that 0.1(PtMnFeCoNi)/TiO₂ achieved complete oxidation of CO at 230 °C, and its catalytic oxidation ability was significantly better than that of the corresponding monometallic and bimetallic catalysts. The high-entropy component adjusts the electronic environment between the TiO₂ support and the metal to promote the reduction of the Ti_3d band gap, enhances the electron-induced ability of the catalytic system to gas molecules (CO and O₂), and exhibits excellent resistance to SO₂ and H₂O. The work is of great significance to understand the synergistic regulation of catalyst activity by multiple metal at the atomic level and provides a strategy for effectively reducing the content of precious metals in the catalyst.

The electrocatalytic oxidation of glycerol toward formic acid is one of the most promising pathways for transformation and utilization of glycerol. Herein, a series of well-defined Ni_n(SR)_2n nanoclusters (n = 4, 5, 6; denoted as Ni NCs) were prepared for the electrocatalytic glycerol oxidation toward formic acid, in which Ni₆-PET-50CV afforded the most excellent electrocatalytic performance with a high formic acid selectivity of 93% and a high glycerol conversion of 86%. This was attributed to the lowest charge transfer impedance and the most rapid reaction kinetics. Combined electrochemical measurements and X-ray absorption fine structure measurements revealed that the structures of Ni NCs remained intact after CV scanning pretreatment and electrocatalysis via forming the Ni-O bond. Additionally, the kinetic studies and in-situ Fourier transformed infrared suggested a sequential oxidation mechanism, in which the main reaction steps of glycerol → glyceraldehyde → glyceric acid were very rapid to produce a high selectivity of formic acid even though the low glycerol conversion. This work presents an opportunity to study Ni NCs for the efficient electrocatalytic oxidation of biomass-derived polyhydroxyl platform molecules to produce value-added carboxylic acids.

Copper (Cu)-based catalysts show significant potential for producing high value-added C₂₊ products in electrocatalytic CO₂/CO reduction reactions (CO₍₂₎RR). However, the structural reconfiguration during operation poses substantial challenges in identifying the intrinsic catalytic active site, especially under similar mass transport conditions. Herein, three typical and commercial Cu-based catalysts (Cu, CuO, and Cu₂O) are chosen as representatives to elucidate the structure-activity relationship of CORR in the membrane electrode assembly electrolyzer. Notably, only the Cu catalyst demonstrates the most suppression of hydrogen evolution reaction, thus achieving the highest FE of 86.7% for C₂₊ products at a current density of 500 mA cm^-2 and maintaining a stable electrolysis over 110 h at a current of 200 mA cm^-2. The influence of chemical valence state of Cu, electrochemical surface area, and local pH were firstly investigated and ruled out for the significant FE differences. Finally, based on the structure analysis from high resolution transmission electron microscope, OH^- adsorption, in situ infrared spectroscopy and density functional theory calculations, it is suggested that the asymmetric C-C coupling (via *CHO and *CO) is the most probable reaction pathway for forming C₂₊ products, with Cu (100)-dominant grain boundaries (GBs) being the most favorable active sites. These findings provide deeper insights into the synergistic relationship between crystal facets and GBs in electrocatalytic systems.

AD-substituted furfurylamines (FAs) are valuable precursors for producing pharmacologically active compounds and polymers. However, enzymatic synthesis of the type of chemicals is still in its infancy. Here we report an imine reductase from Streptomyces albidoflavus (SaIRED) for the reductive amination of biobased furans. A simple, fast and interference-resistant high-throughput screening (HTS) method was developed, based on the coloration reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine. The reductive amination activity of IREDs can be directly indicated by a colorimetric assay. With the reductive amination of furfural with allylamine as the model reaction, SaIRED with the activity of 4.8 U mg^-1 was subjected to three rounds of protein engineering and screening by this HTS method, affording a high-activity tri-variant I127V/D241A/A242T (named M3, 20.2 U mg^-1). The variant M3 showed broad substrate scope, and enabled efficient reductive amination of biobased furans with a variety of amines including small aliphatic amines and sterically hindered amines, giving the target FAs in yields up to >99%. In addition, other variants were identified for preparative-scale synthesis of commercially interesting amines such as N-2-(methylsulfonyl)ethyl-FA by the screen method, with isolated yields up to 87% and turnover numbers up to 9700 for enzyme. Gram-scale synthesis of N-allyl-FA, a valuable building block and potential polymer monomer, was implemented at 0.25 mol L^-1 substrate loading by a whole-cell catalyst incorporating variant M3, with 4.7 g L^-1 h^-1 space-time yield and 91% isolated yield.

Precise regulation of atomic and electronic structures of two-dimensional tungsten disulfide (WS₂) is significant for rational design of high-performance and low-cost catalyst for acetylene hydrogenation to ethylene (AHE), yet remains a major challenge. Herein, we report that by substituting a W atom of WS₂ with a series of transition metal atoms, sulfur vacancy-confined Cu in the WS₂ basal plane (Cu@WS₂-Sv) is theoretically screened as a superior non-noble metal-based catalyst with higher activity, selectivity, and stability for the AHE than other candidates. The co-adsorption of C₂H₂ and H₂ and hydrogenation of C₂H₃* to C₂H₄* are revealed as the key steps establishing a volcano-like activity trend among the candidates, which present Cu@WS₂-Sv as the optimum catalyst combined with molecular dynamics and reaction kinetics analyses. The kinetically more favorable desorption of C₂H₄ than the over hydrogenation path validates a higher selectivity toward C₂H₄ over C₂H₆. Furthermore, a machine-learning model reveals the significant effect of d-electron number and electronegativity of the metal heteroatoms in modulating the AHE activity.

In this study, we developed a tandem photo-assisted electrochemical (PA-EC) chemical strategy for both energy-saving ammonia/fertilizer synthesis and comprehensive nitrogen- and phosphorus-rich wastewater treatment, in which synchronous hypophosphite ion (H₂PO₂^-) oxidation to phosphate ion (PO₄^3-) (POR) and nitrate reduction (NO₃RR) to ammonia (NH₃) occur, followed by cascade chemical precipitation to generate struvite. Herein, a bifunctional Cu₂O@NiFe₂O₄ Z-scheme heterojunction with a yolk/shell structure and oxygen vacancies (O_Vs) was designed and developed to optimize the NO₃RR/POR. Serving as a key component, the established PA-EC system consisted of a Janus Cu₂O@NiFe₂O₄/NF self-supporting integrated photocathode and a Cu₂O@NiFe₂O₄/NF photocathode with efficient struvite PA-EC synthesis performance under a low cell voltage of 1.6 V vs NHE. Specifically, Janus Cu₂O@NiFe₂O₄/NF photocathode exhibits superior performance with a high NH₃ yield of 38.06 mmol L^-1 and a faradaic efficiency (FE) of 92.31% at 1.6 V vs. NHE and enables ammonia FE over 60% in a broad NO₃^- concentration window of 0.005-0.5 mol L^-1. The photoassisted electrochemical catalytic mechanism and reaction pathway for struvite synthesis on Cu₂O@NiFe₂O₄ were investigated through a series of experiments and theoretical calculations. The results demonstrated the critical roles of the interfacial electric field, void confinement, and oxygen vacancies in promoting the overall catalytic efficiency. These encouraging results warrant further studies on combined P and N recovery for efficient production of valuable fertilizers.