Engineering Shewanella oneidensis-Carbon Felt Biohybrid Electrode Decorated with Bacterial Cellulose Aerogel-Electropolymerized Anthraquinone to Boost Energy and Chemicals Production.

Interfacial electron transfer between electroactive microorganisms (EAMs) and electrodes underlies a wide range of bio-electrochemical systems with diverse applications. However, the electron transfer rate at the biotic-electrode interface remains low due to high transmembrane and cell-electrode interfacial electron transfer resistance. Herein, a modular engineering strategy is adopted to construct a Shewanella oneidensis-carbon felt biohybrid electrode decorated with bacterial cellulose aerogel-electropolymerized anthraquinone to boost cell-electrode interfacial electron transfer. First, a heterologous riboflavin synthesis and secretion pathway is constructed to increase flavin-mediated transmembrane electron transfer. Second, outer membrane c-Cyts OmcF is screened and optimized via protein engineering strategy to accelerate contacted-based transmembrane electron transfer. Third, a S. oneidensis-carbon felt biohybrid electrode decorated with bacterial cellulose aerogel and electropolymerized anthraquinone is constructed to boost the interfacial electron transfer. As a result, the internal resistance decreased to 42 Ω, 480.8-fold lower than that of the wild-type (WT) S. oneidensis MR-1. The maximum power density reached 4286.6 ± 202.1 mW m-2, 72.8-fold higher than that of WT. Lastly, the engineered biohybrid electrode exhibited superior abilities for bioelectricity harvest, Cr6+ reduction, and CO2 reduction. This study showed that enhancing transmembrane and cell-electrode interfacial electron transfer is a promising way to increase the extracellular electron transfer of EAMs.

Boosting Interfacial Electron Transfer and CO2 Enrichment on ZIF-8/ZnTe for Selective Photoelectrochemical Reduction of CO2 to CO.

Artificial photosynthesis is an effective way of converting CO2 into fuel and high value-added chemicals. However, the sluggish interfacial electron transfer and adsorption of CO2 at the catalyst surface strongly hamper the activity and selectivity of CO2 reduction. Here, we report a photocathode attaching zeolitic imidazolate framework-8 (ZIF-8) onto a ZnTe surface to mimic an aquatic leaf featuring stoma and chlorophyll for efficient photoelectrochemical conversion of CO2 into CO. ZIF-8 possessing high CO2 adsorption capacity and diffusivity has been selected to enrich CO2 into nanocages and provide a large number of catalytic active sites. ZnTe with high light-absorption capacity serves as a light-absorbing layer. CO2 molecules are collected in large nanocages of ZIF-8 and delivered to the ZnTe surface. As evidenced by scanning electrochemical microscopy, the interface can effectively boost interfacial electron transfer kinetics. The ZIF-8/ZnTe photocathode with unsaturated Zn-Nx sites exhibits a high Faradaic efficiency for CO production of 92.9% and a large photocurrent of 6.67 mA·cm-2 at -2.48 V (vs Fc/Fc+) in a nonaqueous electrolyte at AM 1.5G solar irradiation (100 mW·cm-2).

Work Function-Guided Electrocatalyst Design.

The development of high-performance electrocatalysts for energy conversion reactions is crucial for advancing global energy sustainability. The design of catalysts based on their electronic properties (e.g., work function) has gained significant attention recently. Although numerous reviews on electrocatalysis have been provided, no such reports on work function-guided electrocatalyst design are available. Herein, a comprehensive summary of the latest advancements in work function-guided electrocatalyst design for diverse electrochemical energy applications is provided. This includes the development of work function-based catalytic activity descriptors, and the design of both monolithic and heterostructural catalysts. The measurement of work function is first discussed and the applications of work function-based catalytic activity descriptors for various reactions are fully analyzed. Subsequently, the work function-regulated material-electrolyte interfacial electron transfer (IET) is employed for monolithic catalyst design, and methods for regulating the work function and optimizing the catalytic performance of catalysts are discussed. In addition, key strategies for tuning the work function-governed material-material IET in heterostructural catalyst design are examined. Finally, perspectives on work function determination, work function-based activity descriptors, and catalyst design are put forward to guide future research. This work paves the way to the work function-guided rational design of efficient electrocatalysts for sustainable energy applications.

Magnetic porous microspheres enhancing the anaerobic digestion of sewage sludge: Synergistic free and attached methanogenic consortia.

The addition of exogenous materials is a commonly reported method for promoting the anaerobic digestion (AD) of sludge. However, most exogenous materials are nano-sized and their use encounters problems relating to a need for continuous replenishment, uncontrollability and non-recyclability. Here, magnetic porous microspheres (MPMs), which can be controlled by magnetic forces, were prepared and used to enhance the methanogenesis of sludge. It was observed that the MPMs were spherical particles with diameters of approximately 100 µm and had a stable macroporous hybrid structure of magnetic cores and polymeric shells. Furthermore, the MPMs had good magnetic properties and a strong solid-liquid interfacial electron transfer ability, suggesting that MPMs are excellent carriers for methanogenic consortia. Experimental results showed that the addition of MPMs increased methane production and the proportion of methane in biogas from AD by 100.0 % and 21.2 %, respectively, indicating the MPMs notably enhanced the methanogenesis of sludge. Analyses of variations in key enzyme activities and electron transfer in sludge samples with and without MPMs in AD revealed that the MPMs significantly enhanced the activities of key enzymes involved in hydrolysis, acidification and methanation. This was achieved mainly by enhancing the extracellular electron transfer to strengthen the proton motive force on the cell membrane, which provides more energy generation for methanogenic metabolism. A careful examination of the variations in the morphology, pore structure and magnetism of the MPMs before and after AD revealed that the MPMs increased the prevalence of many highly active anaerobes, and that this did not weaken the magnetic performance. The microbial community structure and metatranscriptomic analysis further indicated that the acetotrophic methanogens (i.e., Methanosaeta) were mainly in a free state and that CO2-reducing methanogens (i.e., Methanolinea and Methanobacterium) mainly adhered to the MPMs. The above synergistic metabolism led to efficient methanogenesis, which indicates that the MPMs optimised the spatial ecological niche of methanogenic consortia. These findings provide an important reference for the development of magnetic porous materials promoting AD.

BODIPY Chemisorbed on SnO2 and TiO2 Surfaces for Photoelectrochemical Applications.

Advancement toward dye-sensitized photoelectrochemical cells to produce solar fuels by solar-driven water splitting requires a photosensitizer that is firmly attached to the semiconducting photoelectrodes. Covalent binding enhances the efficiency of electron injection from the photoexcited dye into the metal oxide. Optimization of charge transfer, efficient electron injection, and minimal electron-hole recombination are mandatory for achieving high efficiencies. Here, a BODIPY-based dye exploiting a novel surface-anchoring mode via boron is compared to a similar dye bound by a traditional carboxylic acid anchoring group. Through terahertz and transient absorption spectroscopic studies, along with interfacial electron transfer simulations, we find that, when compared to the traditional carboxylic acid anchoring group, electron injection of boron-bound BODIPY is faster into both TiO2 and SnO2. Although the surface coverage is low compared with carboxylic acids, the binding stability is improved over a wide range of pH. Subsequent photoelectrochemical studies using a sacrificial electron donor showed that this combined dye and anchoring group maintained photocurrent with good stability over long-time irradiation. This recently discovered binding mode of BODIPY shows excellent electron injection and good stability over time, making it promising for future investigations.

NH2-MIL-101(Fe)-mediated photo-Fenton reaction enhanced simultaneous removal of nitrogen and refractory organics in anammox process through interfacial electron transfer.

In this study, H2O2 (0.1 ‰) and NH2-MIL-101(Fe)-driven (150 mg/L) photo-Fenton-coupled anammox were proposed to simultaneously improve the removal efficiency of nitrogen and humic acid. Long-term experiments showed that the total nitrogen removal efficiency was increased by the photo-Fenton reaction to 91.9 ± 1.5 % by altering the bioavailability of refractory organics. Correspondingly, the total organic carbon removal efficiency was significantly increased. Microbial community analyses indicated that Candidatus_Brocadia maintained high activity during photo-Fenton reaction and was the most abundant genus in the reactor. Dissimilatory nitrate reduction to ammonium process and denitrification process were enhanced, resulting in reduced NO3--N production. The establishment of electron transfer between microorganisms and NH2-MIL-101 (Fe) improved the charge separation efficiency of the quantum dots and increased the intracellular adenosine triphosphate content of anammox bacteria. These results indicated that photo-Fenton-anammox process promoted the removal of nitrogen and refractory organics in one reactor which had good economic value and application prospects.

Photolysis of Dissolved Organic Matter over Hematite Nanoplatelets.

Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe(III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation. DFT calculations confirmed that Fe(II) on the hematite (001) surface, created by interfacial electron transfer from photoexcited chromophores in DOM, can reduce dioxygen molecules to superoxide radicals (•O2-) through a one-electron transfer process. 1H nuclear magnetic resonance (NMR) and electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) spectroscopies show that the association of DOM with hematite enhances the cleavage of aromatic groups during photodegradation. The findings point to a pivotal role for organic matter at the interface that guides specific ROS generation and the subsequent photodegradation process, as well as the prospect of using ROS signatures as a forensic tool to help interpret more complicated field-relevant systems.

Interfacial Electron Transfer in Chemical and Biological Transformation of Pollutants in Environmental Catalysis.

Interfacial electron transfer (IET) is essential for chemical and biological transformation of pollutants, operative across diverse lengths and time scales. This Perspective presents an array of multiscale molecular simulation methodologies, supplemented by in situ monitoring and imaging techniques, serving as robust tools to decode IET enhancement mechanisms such as interface molecular modification, catalyst coordination mode, and atomic composition regulation. In addition, three IET-based pollutant transformation systems, an electrocatalytic oxidation system, a bioelectrochemical spatial coupling system, and an enzyme-inspired electrocatalytic system, were developed, demonstrating a high effect in transforming and degrading pollutants. To improve the effectiveness and scalability of IET-based strategies, the refinement of these systems is necessitated through rigorous research and theoretical exploration, particularly in the context of practical wastewater treatment scenarios. Future endeavors aim to elucidate the synergy between biological and chemical modules, edit the environmental functional microorganisms, and harness machine learning for designing advanced environmental catalysts to boost efficiency. This Perspective highlights the powerful potential of IET-focused environmental remediation strategies, emphasizing the critical role of interdisciplinary research in addressing the urgent global challenge of water pollution.

Enabling Internal Electric Field in Heterogeneous Nanosheets to Significantly Accelerate Alkaline Hydrogen Electrocatalysis.

Efficient bifunctional hydrogen electrocatalysis, encompassing both hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR), is of paramount significance in advancing hydrogen-based societies. While non-precious-metal-based catalysts, particularly those based on nickel (Ni), are essential for alkaline HER/HOR, their intrinsic catalytic activity often falls short of expectations. Herein, an internal electric field (IEF) strategy is introduced for the engineering of heterogeneous nickel-vanadium oxide nanosheet arrays grown on porous nickel foam (Ni-V2 O3 /PNF) as bifunctional electrocatalysts for hydrogen electrocatalysis. Strikingly, the Ni-V2 O3 /PNF delivers 10 mA cm-2 at an overpotential of 54 mV for HER and a mass-specific kinetic current of 19.3 A g-1 at an overpotential of 50 mV for HOR, placing it on par with the benchmark 20% Pt/C, while exhibiting enhanced stability in alkaline electrolytes. Density functional theory calculations, in conjunction with experimental characterizations, unveil that the interface IEF effect fosters asymmetrical charge distributions, which results in more thermoneutral hydrogen adsorption Gibbs free energy on the electron-deficient Ni side, thus elevating the overall efficiency of both HER and HOR. The discoveries reported herein guidance are provided for further understanding and designing efficient non-precious-metal-based electrocatalysts through the IEF strategy.

Ultrasound-Induced Abiotic and Biotic Interfacial Electron Transfer for Efficient Treatment of Bacterial Infection.

Electron transfer plays an important role in various catalytic reactions and physiological activities, whose altered processes may change catalytic efficiency and interfere in physiological metabolic processes. In this study, we design an ultrasound (US)-activated piezoelectric responsive heterojunction (PCN-222-BTO, PCN: porous coordination network), which can change the electron transfer path at the abiotic and abiotic-biotic interfaces under US, thus achieving a rapid (15 min) and efficient bactericidal effect of 99.96%. US-induced polarization of BTO generates a built-in electric field, which promotes the electron transfer excited from PCN-222 to BTO at the PCN-222-BTO interface, thereby increasing the level of reactive oxygen species (ROS) production. Especially, we find that the biological electron transfer from the bacterial membrane to BTO is also activated at the MRSA-BTO interface. This antibacterial mode results in the down-regulated ribosomal, DNA and ATP synthesis related genes in MRSA, while the cell membrane and ion transport related genes are up-regulated due to the synergistic damage effect of ROS and disturbance of the bacterial electron transport chain. This US responsive dual-interface system shows an excellent therapeutic effect for the treatment of the MRSA-infected osteomyelitis model, which is superior to clinical vancomycin therapy.

CoMoO4-CoP/NC heterostructure anchored on hollow polyhedral N-doped carbon skeleton for efficient water splitting.

We report the synthesis and electrocatalytic properties of a CoMoO4-CoP heterostructure anchored on a hollow polyhedral N-doped carbon skeleton (CoMoO4-CoP/NC) for water-splitting applications. The preparation involved the anion exchange of MoO42- to the organic ligand of ZIF-67, the self-hydrolysis of MoO42-, and NaH2PO2 phosphating annealing. CoMoO4 was found to enhance thermal stability and prevent active site agglomeration during annealing, while the hollow structure of CoMoO4-CoP/NC provided a large specific surface area and high porosity that facilitated mass transport and charge transfer. The interfacial electron transfer from Co to Mo and P sites promoted the generation of electron-deficient Co sites and electron-enriched P sites, which accelerated water dissociation. CoMoO4-CoP/NC exhibited excellent electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH solution, with overpotentials of 122 mV and 280 mV at 10 mA cm-2, respectively. The CoMoO4-CoP/NC‖CoMoO4-CoP/NC two-electrode system only required an overall water splitting (OWS) cell voltage of 1.62 V to achieve 10 mA cm-2 in an alkaline electrolytic cell. In addition, the material showed comparable activity to 20% Pt/C‖RuO2 in a pure water home-made membrane electrode device, demonstrating potential for practical applications in proton exchange membrane (PEM) electrolyzers. Our results suggest that CoMoO4-CoP/NC is a promising electrocatalyst for efficient and cost-effective water splitting.

Modulating Water Splitting Kinetics via Charge Transfer and Interfacial Hydrogen Spillover Effect for Robust Hydrogen Evolution Catalysis in Alkaline Media.

Designing and synthesizing advanced electrocatalysts with superior intrinsic activity toward hydrogen evolution reaction (HER) in alkaline media is critical for the hydrogen economy. Herein, a novel Ir@Rhene heterojunction electrocatalyst is synthesized via epitaxially confining ultrasmall and low-coordinate Ir nanoclusters on the ultrathin Rh metallene accompanying the formation of Ir/IrO2 Janus nanoparticles. The as-prepared heterojunctions display outstanding alkaline HER activity, with an overpotential of only 17 mV at 10 mA cm-2 and an ultralow Tafel slope of 14.7 mV dec-1 . Both structural characterizations and theoretical calculations demonstrate that the Ir@Rhene heterointerfaces induce charge density redistribution, resulting in the increment of the electron density around the O atoms in the IrO2 site and thus delivering much lower water dissociation energy. In addition, the dual-site synergetic effects between IrO2 and Ir/Rh interface trigger and improve the interfacial hydrogen spillover, thereby subtly avoiding the steric blocking of the active site and eventually accelerating the alkaline HER kinetics.

Fe(II)-Catalyzed Transformation of Ferrihydrite with Different Degrees of Crystallinity.

Natural occurring ferrihydrite (Fh) nanoparticles have varying degrees of crystallinity, but how Fh crystallinity affects its transformation behavior remains elusive. Here, we investigated the Fe(II)-catalyzed transformation of Fh with different degrees of crystallinity (i.e., Fh-2h, Fh-12h, and Fh-85C). X-ray diffraction patterns of Fh-2h, Fh-12h, and Fh-85C exhibited two, five, and six diffraction peaks, respectively, indicating the order of crystallinity: Fh-2h < Fh-12h < Fh-85C. Fh with the lower crystallinity has a higher redox potential, corresponding to the faster Fe(II)-Fh interfacial electron transfer and Fe(III)labile production. With the increase of initial Fe(II) concentration ([Fe(II)aq]int.) from 0.2 to 5.0 mM, the transformation pathways of Fh-2h and Fh-12h change from Fh → lepidocrocite (Lp) → goethite (Gt) to Fh → Gt, but that of Fh-85C switches from Fh → Gt to Fh → magnetite (Mt). The changes are rationalized using a computational model that quantitatively describes the relationship between the free energies of formation for starting Fh and nucleation barriers of competing product phases. Gt particles from the Fh-2h transformation exhibit a broader width distribution than those from Fh-12h and Fh-85C. Uncommon hexagonal Mt nanoplates are formed from the Fh-85C transformation at [Fe(II)aq]int.= 5.0 mM. The findings are crucial to comprehensively understand the environmental behavior of Fh and other associated elements.

Potential-Modulated Ion Distributions in the Back-to-Back Electrical Double Layers at a Polarised Liquid|Liquid Interface Regulate the Kinetics of Interfacial Electron Transfer.

Biphasic interfacial electron transfer (IET) reactions at polarisable liquid|liquid (L|L) interfaces underpin new approaches to electrosynthesis, redox electrocatalysis, bioelectrochemistry and artificial photosynthesis. Herein, using cyclic and alternating current voltammetry, we demonstrate that under certain experimental conditions, the biphasic 2-electron O2 reduction reaction can proceed by single-step IET between a reductant in the organic phase, decamethylferrocene, and interfacial protons in the presence of O2. Using this biphasic system, we demonstrate that the applied interfacial Galvani potential difference Δ o w φ provides no direct driving force to realise a thermodynamically uphill biphasic IET reaction in the mixed solvent region. We show that the onset potential for a biphasic single-step IET reaction does not correlate with the thermodynamically predicted standard Galvani IET potential and is instead closely correlated with the potential of zero charge at a polarised L|L interface. We outline that the applied Δ o w φ required to modulate the interfacial ion distributions, and thus kinetics of IET, must be optimised to ensure that the aqueous and organic redox species are present in substantial concentrations at the L|L interface simultaneously in order to react.

Single-Site SnOCu Pairs with Interfacial Electron Transfer Effect for Enhanced Electrochemical Catalysis and Sensing.

As advanced electrochemical catalysts, single-atom catalysts have made great progress in the field of catalysis and sensing due to their high atomic utilization efficiency and excellent catalytic performance. Herein, stannum-doped copper oxide (CuOSn1 ) nanosheets with single-site SnOCu pairs as active sites are synthesized as electrocatalysts for biological molecule detection. Compared with CuO-based electrochemical sensors, the CuOSn1 -based electrochemical sensors have improved detection sensitivity with a rapid electrochemical response. Theoretical calculation reveals that the single-site SnOCu pairs induced interfacial electronic transfer effect can strengthen hydroxy adsorption and thus reduce the energy barrier of the biological molecule oxidation process. As a concept application, electrochemical detection of dopamine and uric acid molecules is achieved, exhibiting satisfactory sensitivity and selectivity. This work demonstrates the advantages of single-site SnOCu pairs in electrochemical catalysis and sensing, which provides theoretical guidance for understanding the structure-activity relationship for sensitive electrochemical sensing.

Effect of Stoichiometry on Nanomagnetite Sulfidation.

Magnetite (Mt) has long been regarded as a stable phase with a low reactivity toward dissolved sulfide, but natural Mt with varying stoichiometries (the structural Fe(II)/Fe(III) ratio, xstru) might exhibit distinct reactivities in sulfidation. How Mt stoichiometry affects its sulfidation processes and products remains unknown. Here, we demonstrate that xstru is a master variable controlling the rates and extents of sulfide oxidation by magnetite nanoparticles (11 ± 2 nm). At pH = 7.0-8.0 and the initial Fe/S molar ratio of 10-50, the partially oxidized magnetite (xstru = 0.19-0.43) can oxidize dissolved sulfide to elemental sulfur (S0), but only surface adsorption of sulfide, without interfacial electron transfer (IET), occurs on the nearly stoichiometric magnetite (xstru = 0.47). The higher initial rate and extent of sulfide oxidation and S0 production are observed with the more oxidized magnetite that has the higher electron-accepting capability from surface-complexed sulfide (S(-II)(s)). The FeS clusters formed from magnetite sulfidation can be oxidized by the most oxidized magnetite with xstru = 0.19 but not by other magnetite particles. A linear relationship between the Gibbs free energy of reaction and the surface area-normalized initial rate of sulfide oxidation is observed in all experiments under the different conditions, suggesting the S(-II)(s)-magnetite IET dominates magnetite sulfidation at high Fe/S molar ratios and near-neutral pH.

Hematite-mediated Mn(II) abiotic oxidation under oxic conditions: pH effect and mineralization.

Interactions between manganese (Mn) and iron (Fe) are widespread processes in soils and sediments, however, the abiotic transformation mechanisms are not fully understood. Herein, Mn(II) oxidation on hematite were investigated at various pH under oxic condition. Mn(II) oxidation rates increased from 3 × 10-4 to 8 × 10-2 h-1 as pH increased from 7.0 to 9.0, whereas hematite enhanced Mn(II) oxidation rates to 1 h-1. During oxidation process, high pH could promote the oxidation of Mn(II) into Mn minerals, resulting in the rapid consumption of the newly-formed H+, and high pH facilitated Mn(II) adsorption and oxidation by altering Mn(II) reactivity and speciation. Only granule-like hausmannite was found on the hematite surface at pH 7.0, whereas hausmannite particles and feitknechtite and manganite nanowires were formed at pH from 7.5 to 9.0. Moreover, a co-shell structured nanowire composed of manganite and feitknechtite was observed owing to autocatalytic reactions. Specifically, electron transfers between Mn(II) and O2 occurred on the surface or through bulk phase of hematite, and direct electron transfers in the O2-Mn(II) complex and indirect electron transfers in the O2-Fe(II/III)-Mn(II) complex may both have contribution to the overall reactions. The findings provide a comprehensive interpretation of Fe-Mn interaction and have implications for the formation of soil Fe-Mn oxyhydroxides with unique properties in controlling element cycling.

Modulating Hydrogen Adsorption via Charge Transfer at the Semiconductor-Metal Heterointerface for Highly Efficient Hydrogen Evolution Catalysis.

Designing and synthesizing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is important for realizing the hydrogen economy. Tuning the electronic structure of the electrocatalysts is essential to achieve optimal HER activity, and interfacial engineering is an effective strategy to induce electron transfer in a heterostructure interface to optimize HER kinetics. In this study, ultrafine RhP2 /Rh nanoparticles are synthesized with a well-defined semiconductor-metal heterointerface embedded in N,P co-doped graphene (RhP2 /Rh@NPG) via a one-step pyrolysis. RhP2 /Rh@NPG exhibits outstanding HER performances under all pH conditions. Electrochemical characterization and first principles density functional theory calculations reveal that the RhP2 /Rh heterointerface induces electron transfer from metallic Rh to semiconductive RhP2 , which increases the electron density on the Rh atoms in RhP2 and weakens the hydrogen adsorption on RhP2 , thereby accelerating the HER kinetics. Moreover, the interfacial electron transfer activates the dual-site synergistic effect of Rh and P of RhP2 in neutral and alkaline environments, thereby promoting reorganization of interfacial water molecules for faster HER kinetics.

Low-Temperature-Processed Monolayer Inverse Opal SnO2 Scaffold for Efficient Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells (PSCs) have attracted tremendous attention in the photovoltaic field due to their excellent optical properties and simple fabrication process. However, the recombination of photogenerated electron-hole pairs at the interface severely affects the power conversion efficiency (PCE) of the PSCs. Herein, a monolayer of inverse opal SnO2 (IO-SnO2 ) is synthesized via a template-assisted method and used as a scaffold for perovskite layer (PSK). The porous IO-SnO2 scaffold increases the contact area and shortens the transport distance between the electron transport layer (ETL) and PSK. Ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy results indicate that the built-in electric field is enhanced with IO-SnO2 scaffold, strengthening the driving force for charge separation. Femtosecond transient absorption spectroscopy measurements reveal that the IO-SnO2 scaffold facilitates interfacial electron transfer from PSK to ETL. Based on the above superiorities, the IO-SnO2 -based PSCs exhibit boosted PCE and device stability compared with the pristine PSCs. This work provides insights into the development of novel scaffold layers for high-performance PSCs.

Electron-pool promotes interfacial electron transfer efficiency between pyrogenic carbon and anodic microbes.

Relying on surface functional groups and graphitized structure, pyrogenic carbon (PC) was reported to facilitate microbial extracellular electron transfer (EET), which plays a crucial role in diverse biogeochemical reactions. However, little is known about the role of electrical capacitance on EET between microbes and PCs. Here, PCs were obtained from fermented steam bread after carbonization at different temperatures from 700 °C to 1100 °C. PC-900 exhibited the lowest charge transfer resistance and highest electrical capacitance, ascribed to combined effects of graphitic structure and hierarchical porous structure. The interfacial EET was further investigated by enriching electroactive biofilms on PC surface. Faster interfacial EET was demonstrated in PC-900. Maximum power density was proportional to electrical capacitance rather than conductivity. PC-900 enriched the most Geobacter sp., which was positively correlated with electrical capacitance according to the distance-based redundancy analysis. Electrical capacitance was suggested to act as electron pool to facilitate interfacial EET efficiency.