Electrochemical Hydrogen Evolution Research Articles

Hydride‐containing 2‐Electron Pd/Cu Superatoms as Catalysts for Efficient Electrochemical Hydrogen Evolution

AbstractThe first hydride‐containing 2‐electron palladium/copper alloys, [PdHCu11{S2P(OiPr)2}6(C≡CPh)4] (PdHCu11) and [PdHCu12{S2P(OiPr)2}5{S2PO(OiPr)} (C≡CPh)4] (PdHCu12), are synthesized from the reaction of [PdH2Cu14{S2P(OiPr)2}6(C≡CPh)6] (PdH2Cu14) with trifluoroacetic acid (TFA). X‐ray diffraction reveals that the PdHCu11 and PdHCu12 kernels consist of a central PdH unit encapsulated within a vertex‐missing Cu11 cuboctahedron and complete Cu12 cuboctahedron, respectively. DFT calculations indicate that both PdHCu11 and PdHCu12 can be considered as axially‐distorted 2‐electron superatoms. PdHCu11 shows excellent HER activity, unprecedented within metal nanoclusters, with an onset potential of −0.05 V (at 10 mA cm−2), a Tafel slope of 40 mV dec−1, and consistent HER activity during 1000 cycles in 0.5 M H2SO4. Our study suggests that the accessible central Pd site is the key to HER activity and may provide guidelines for correlating catalyst structures and HER activity.

Design and fabrication of bimetallic Co-Ni phosphides on WC-Co-Ni cemented carbide substrate for electrochemical hydrogen evolution reaction

An innovative approach was proposed to recycle WC-Co-Ni cemented carbides via synthesizing bimetallic cobalt-nickel phosphides on the waste cemented carbides substrate for producing renewable hydrogen by the electrolysis of water. WC-Co-Ni cemented carbides with tunable Co/Ni ratios were prepared through the traditional powder metallurgy method. Co-Ni-P catalysts on self-supported Co-Ni porous substrates were prepared by a two-step method of etching WC grains and phosphatizing treatments. The bimetallic phosphides exhibited the excellent activities which were strongly dependent on the Co/Ni ratios. With an optimal Ni content of 50 wt% in the binder phase, the prepared materials required a low overpotential of 126 mV for achieve a current density of 10 mA cm−2. The uniformly distributed CoNiP catalyst on the Co-Ni skeleton demonstrated the highest catalytic activity due to the synergistic interaction among the abundant exposed phosphide sites, enhanced mass transfer pathways and reduced energy barrier. This work provided a feasible strategy for the recycle of waste WC-Co-Ni cemented carbides and the design of bimetallic phosphide catalysts for HER.

Comparative Studies of g-C3N4 and C3N3S3 Organic Semiconductors-Synthesis, Properties, and Application in the Catalytic Oxygen Reduction.

Exfoliated g-C3N4 is a well-known semiconductor utilized in heterogenous photocatalysis and water splitting. An improvement in light harvesting and separation of photogenerated charge carriers may be obtained by polymer doping with sulfur. In this work, we incorporate sulfur into the polymer chain by chemical polymerization of trithiocyanuric acid (C3N3S3H3) to obtain C3N3S3. The XRD measurements and TEM images indicated that C3N3S3, in contrast to g-C3N4, does not exist in the form of a graphitic structure and is not exfoliated into thin lamellas. However, both polymers have similar optical properties and positions of the conduction and valence bands. The comparative studies of electrochemical oxygen reduction and hydrogen evolution indicated that the overpotentials for the two processes were smaller for C3N3S3 than for g-C3N4. The RDE experiments in the oxygen-saturated solutions of 0.1 M NaOH have shown that O2 is electrochemically reduced via the serial pathway with two electrons involved in the first step. The spectroscopic experiments using NBT demonstrated that both polymers reveal high activity in the photocatalytic reduction of oxygen to superoxide anion radical by the photogenerated electrons.

Zr-MOF/NiS2 hybrids on nickel foam as advanced electrocatalysts for efficient hydrogen evolution

As a typical transition-metal sulfides (TMS), nickel disulfide (NiS2) has attracted great attention in terms of hydrogen evolution reaction (HER). Howbeit, owing to the poor conductivity, slow reaction kinetics and instability of NiS2, its HER activity is still necessary to be improved. In this work, we designed hybrid structures consisting of the nickel foam (NF) as a self-supporting electrode, NiS2 derived from the sulfuration of NF and Zr-MOF grown on the surface of NiS2@NF (Zr-MOF/NiS2@NF). Due to the synergistic effect between the different constituents, the obtained Zr-MOF/NiS2@NF demonstrates ideal electrochemical hydrogen evolution ability in acidic and alkalescent environment, reaching a standard current density of 10 mA cm−2 at overpotentials of 110 and 72 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively. What is more, it also maintains excellent electrocatalytic durability for 10 h in both electrolytes. This work could provide a useful guidance on effectively combining metal sulfide with MOF for high-performance HER electrocatalysts.

Double perovskite La2MnCoO6 nanoparticles as promising catalysts for electro-chemical hydrogen evolution reactions

Double perovskite La2MnCoO6 (LMCO) nanoparticles have been synthesized by a molten salt method and used as promising catalysts for electro-chemical hydrogen evolution reactions (HERs). An average size of LMCO nanoparticles was estimated approximately 65 nm from electron microscopy. LMCO nanoparticles crystallize in a monoclinic structure (space group of P21/n). The refined lattice constants of “a” = 5.5038(2) Å, “b” = 5.4462(4) Å, “c” = 7.7547(4) Å, and “β” = 90.050(3)°. LMCO nanoparticles exhibit promising catalytic performances for electro-chemical HERs with a low Tafel slope value (190 mV/dec). The onset over-potential for HERs was found to be approximately 120 mV, which is in good agreement with the reported onset over-potentials of other electro-catalysts for HER. The stability tests confirm that the electrode materials are stable and efficient electro-catalysts for HERs. This is noteworthy that the double perovskites are recognized as promising alternates for precious electro-catalysts.

Gold cluster incorporated Rhenium disulfide: An efficient catalyst towards electrochemical and photoelectrochemical hydrogen evolution reaction

Rhenium disulfide (ReS2) is an emerging member of the transition metal dichalcogenide (TMD) family. It attracts recent research interest due to its tunable bandgap, weak interlayer coupling, and layer-independent optoelectronic properties. This work demonstrates a gold cluster incorporated ReS2 as a robust hydrogen evolution reaction (HER) catalyst. Au cluster is synthesized via the solid-state grinding method and mixed with ReS2 by mechanical mixing. The excellent catalytic activity of the ReS2-Au cluster is observed both in photoelectrochemical and electrochemical studies. Synergistic interaction between the Au cluster and ReS2 reinforces light absorption of the ReS2-Au cluster, especially within the visible region, and boosts the photoelectrochemical properties of the composite. The photoelectrochemical mechanism of the ReS2-Au cluster is investigated in detail using Mott-Schottky analysis. This work is anticipated to provide new insight into the photoelectrochemical properties of ReS2 and metal-cluster-sensitized TMD nanocomposites.

Electrochemical Corrosion and Hydrogen Evolution Behavior for Mg and Mg–Al Alloys in Sea Water

Electrochemical Corrosion and Hydrogen Evolution Behavior for Mg and Mg–Al Alloys in Sea Water

Self-assembly of novel cobalt iron phosphate nanoparticles for the solid-state supercapattery and high-performance hydrogen evolution reaction

In this article, we report the preparation of novel cobalt iron phosphate nanoparticles which are self-assembled for energy storage, energy conversion, and sustainability. The self-assembled nanoparticles provide an efficient pathway for the transfer of electrons from the bulk of the materials to the interface of the electrode. This hypothesis has been derived from the analysis based on the electrochemical results for the supercapacitor-based energy storage and hydrogen evolution. The electrode consisting of self-assembled nanoparticles exhibits a maximum specific capacity of 280 C g−1 at a specific current of 1 A g−1. The cyclic voltammetric results suggest the prominent charge storage is by the faradaic reaction which has been concluded from Dunn's approach. The supercapattery device utilizing activated carbon (AC) as the negative electrode and cobalt iron phosphate as the positive electrode exhibit a specific capacity of 210 C g−1 at 2 A g−1 while the specific energy of 47.6 Wh kg-1 at 1.6 kW kg−1. Furthermore, the electrode actively catalyzes the electrochemical hydrogen evolution reaction and it can be lowering the overpotential required by the hydrogen generation. It exhibits the overpotential of 197 mV while the electrode represents the long-time (24 h) consistency for hydrogen production. These results indicate that the novel cobalt iron phosphate nanoparticles could be a potential candidate for energy storage and conversion purposes.

Dual-Functional CuO-Decorated Bi3.84W0.16O6.24/Bi2WO6 Nanohybrids for Enhanced Electrochemical Hydrogen Evolution Reaction and Photocatalytic Cr(VI) Reduction Performance

The development of dual-functional nanohybrid-based electrocatalysts/photocatalysts for producing renewable energy and removing heavy metal pollutants describes an environmentally sustainable technique to address the challenges in energy and environment applications. Herein, we adopted microwave-assisted synthesis to develop CuO-decorated Bi3.84W0.16O6.24/Bi2WO6 (CuO/biphase-BW) dual-functional nanohybrids for electrochemical hydrogen evolution reaction (HER) and photocatalytic Cr(VI) reduction applications. CuO nanoparticles with ∼50 nm were uniformly distributed on an octahedron-shaped bismuth tungstate analyzed via a high-resolution transmission electron microscope technique. Biphase bismuth tungstate optimization was meticulously controlled via the amount of copper precursor added to the reaction. Among synthesized materials, CuO1.0/biphase-BW catalysts exhibit excellent HER activity in neutral media (0.5 M Na2SO4) with a relatively low overpotential of 111 mV at a current density of 10 mA/cm2, and also it exhibits a lower Tafel slope of 237 mV/dec. Moreover, CuO1.0/biphase-BW catalyst-coated carbon cloth exhibits good conductivity and excellent electrochemical stability for 24 h. Maximum photocatalytic reduction of aqueous Cr(VI) was achieved on the CuO1.0/biphase-BW catalyst. It is worth mentioning that the tremendous activity of the synthesized electrocatalyst/photocatalyst can be ascribed to the formation and electronic interaction of CuO with biphase Bi3.84W0.16O6.24/Bi2WO6, thus increasing its surface-active sites and charge transfer. Our work provides a facile and effective way to engineer dual-functional nanohybrids for efficient water splitting in a neutral medium and reducing toxic (Cr(VI)) metal.

Nickel Boride (NixB) Nanocrystals: From Solid-State Synthesis to Highly Colloidally Stable Inks

Metal borides, a class of materials intensively used in industry as superconductors, magnetic materials, or hot cathodes, remain largely unexplored at the nanoscale mainly due to the difficulty in synthesizing single-phase nanocrystals. Recent works have shown that synthetic methods at lower temperatures (<400 °C) yield amorphous polydisperse nanoparticles, while phase purity is an issue at higher temperatures. Among all the metal-rich borides, nickel borides (NixB) could be a potential catalyst for a broad range of applications (hydrogenations, electrochemical hydrogen, and oxygen evolution reactions) under challenging conditions (such as high pH or high temperatures). Here, we report a novel solid-state method to synthesize NixB nanopowders (with a diameter of approximately 45 nm) and their conversion into colloidal suspensions (inks) through treatment of the nanocrystal surface. For the solid-state synthesis, we used commercially available salts and explored the reaction between the Ni and B sources while varying the synthetic parameters under mild and solvent-free reaction conditions. We show that pure phase Ni3B and Ni2B NCs can be obtained with high yield in the pure phase using as precursors NiCl2 and Ni, respectively. Through extensive mechanistic studies, we show that Ni nanoclusters (1–2 nm) are an intermediate in the boriding process, while the metal co-reactant lowers the decomposition temperature of NaBH4 (used as a reducing agent and B source). Size control can instead be exerted through reaction mediators, as seen from the differential nucleation and growth of Ni (clusters) or NixB NCs when employing L- (amine, phosphine) and X-type (carboxylate) mediators. Applying surface engineering methods to our NixB NCs, we stabilized them with inorganic (NOBF4) or organic (borane tert-butyl amine, oleylamine) ligands in the appropriate solvent (DMSO, hexane). With this method, we produce stable inks for further solution processing applications. Our results provide tools for further development of catalysts based on NixB NCs and pave the way for synthesizing other metal boride colloidal nanostructures.

Covalent triazine frameworks based on different stacking model as electrocatalyst for hydrogen evolution

Two-dimensional covalent triazine frameworks (2D-CTFs) are nitrogen-rich conjugated porous polymers with high porosity, adjustable electronic properties and abundant active sites, which are conducive to electrochemical water-splitting. In this work, two kinds of high crystallinity Covalent triazine frameworks (CTFs) with AA and AB stacking models were synthesized by super acid catalytic and crystal transfer via annealing, and this method was extended to fluorinated CTFs. The unique π -conjugated 1D channel in CTFs provide favorable conditions for electron transport and mass diffusion during hydrogen evolution. The catalytic kinetic analysis shows that the catalytic performance of CTFs is related to the stacking configuration. When CTFs are converted into AA stacking, the electrocatalytic activity of CTFs are enhance significantly. Meanwhile, the electrocatalytic performance of CTFs is improved obviously after fluorination. This work provides a more promising direction for finding high activity, stable and cheap electrochemical hydrogen evolution catalysts by changing the stacking patterns.

Electroless deposition of Ni-W-Mo-Co-P films as a binder-free, efficient and durable electrode for electrochemical hydrogen evolution

In this study, the manufacture of Ni-W-Mo-Co-P, Ni-Mo-Co-P, Ni-W-Co-P, Ni-W-Mo -P, Ni-Co-P, Ni-Mo-P, Ni-W-P, and Ni-P alloying coatings through electroless method on the copper substrate was investigated. The elemental and structural tests showed that the alteration of the Ni-P electroless basic bath composition by introducing sodium tungstate, sodium molybdate, and cobalt chloride additives enabled the deposition of alloying coatings. Linear Sweep Voltametry (LSV) tests revealed that the Ni-W-Mo-Co-P sample (NWMCP) coated in an alkaline bath with 18 g/l Nickel (II) sulfate, 12 g/l Ammonium acetate, 12 g/l Sodium citrate, 12 ml Lactic acid, 12 g/l Sodium hypophosphite, 8 g/l Sodium tungstate, 0.2 g/l Sodium molybdate, and 10 g/l Cobalt (II) chloride was featured with the best electrocatalytic properties with η10 = −41, η20 = −46, η100 = −67 mV and tafel slope of 38 mV.dec−1. Scanning Electron Microscope (SEM) observations and Cyclic Voltametry (CV) electrochemical tests showed that morphology had a negligible effect on electrocatalytic performance of the coating. In addition, the presence of alloying elements improved the coating intrinsic properties by changing its electronic structure. Electrocatalytic stability was assessed using chronoamperometry, cyclic voltammetry, and stepwise chronoamperometry tests, introducing NWMCP sample a durable electrode generation with good stability.

Comparative Study on Hydrogen Evolution Reaction of Various Cobalt-Selenide-Based Electrocatalysts

The growth of stable and efficient catalysts is vital for the electrochemical hydrogen evolution reaction (HER). Metal–organic frameworks (MOFs) have been recognized as ideal templates for fabricating efficient nanomaterial-based electrocatalysts for the HER. In this study, nitrogen-containing Co-MOF (ZIF-67), Co-MOF-74, and cobalt chloride salt were selenized to create various cobalt-selenide-based materials, i.e., cobalt selenide@nitrogen-doped carbon (CoSe2@NC), CoSe2@C, and CoSe2, respectively. The core–shell structure of CoSe2@NC originated from ZIF-67 exhibited better HER catalytic activity than those of CoSe2@C and CoSe2. CoSe2@NC exhibited a low overvoltage of 184 mV at 10 mA cm−2 and a small Tafel slope of 58.4 mV dec−1. In addition, this catalyst exhibited excellent durability while maintaining its performance after 12 h of testing. The high catalytic activity is ascribed to the integrated effect of the core–shell architecture, N-doped carbon, and large surface area, making protected active sites, high conductivity, and exposed active sites possible. The results demonstrate the efficiency of using MOFs as precursors for cobalt selenide fabrication and provide a potential synthetic strategy for noble-metal-free electrocatalysts for hydrogen production.

Bimetallic sulfides arrays with three-dimensional nanostructure for efficient electrochemical hydrogen evolution

The efficient and low-cost electrocatalyst for hydrogen evolution reaction (HER) is highly desired to meet the practical needs in scalable production of hydrogen fuel. In this paper, we report a two-step strategy for fabrication of metallic sulfides supported on nanoporous NiFe alloy (S-np-Ni4.5Fe4.5(Al)). When served as an integrated hydrogen evolution cathode, the S-np-Ni4.5Fe4.5(Al) shows remarkable catalytic activity and superior stability in acidic medium, and it needs overpotentials of 81 and 202 mV to achieve current densities of 10 and 100 mA cm−2, respectively. This work offers an attractive way to construct low-cost and high-performance catalyst for large-scale water electrolysis.

Caterpillar-like 3D graphene nanoscrolls@CNTs hybrids decorated with Co-doped MoSe2 nanosheets for electrocatalytic hydrogen evolution

• The CNTs are CVD grown on the surface and inner space of graphene nanoscrolls to form unique caterpillar-like structure. • The caterpillar-like carbon materials as scaffold greatly improve the catalytic activity of active materials (MoSe 2 ). • The encapsulated Ni nanoparticles of unique caterpillar-like structure can optimize the electron structure of the outmost loading (MoSe 2 ) by electron traversing effect. • Electron traversing effect and doping effect can be synergistically applied in elevating catalytic performance. Hydrogen is a clean and flexible energy carrier that has the promising to satisfy urgent demands of the energy crisis and environmental protection. Electrochemical hydrogen evolution reaction (HER), a critical half-reaction in water splitting, is one of the greenest and most common methods to obtain high-purity hydrogen. Designing preeminent activity and stability electrocatalysts for hydrogen precipitation reaction (HER) to reduce energy consumption is of great essential. 3D carbon-based materials have attracted widespread concern as the potential scaffolds of highly active and durable electrocatalysts for HER. To boost the HER activity and prolong the lifespan of electrocatalysts, multifarious 3D carbon architectures make an appearance to be engineered for accelerating electronic/mass transfer and maximizing the exposure of active sites. Herein, we designed and fabricated high-performance electrocatalysts based on a special caterpillar-like 3D graphene nanoscrolls@CNTs (GNS@CNTs) scaffold decorated with Co-doped MoSe 2 nanosheets for HER. In the caterpillar-like hierarchical structure, CNTs were seamlessly co-bonded and dilated the interlayer and outer spacing of GNS through CVD growth technology, and nickel nanoparticles were covered by the CNTs tips. Taking advantage of the plentiful hierarchical pore, larger specific surface area, and higher chemical stability of the caterpillar-like structure, the catalysts exhibited enhanced electrocatalytic properties than some existing data reported. Density functional theory calculations showed that the encapsulated nickel nanoparticle could tune the electronic structure of the outer anchored Co-doped MoSe 2 and optimize its ∆ G of H* adsorption by electron traversing effect and doping effect. These indicate that caterpillar-like GNS@CNT is an ideal scaffold for anchoring actives substance and is suitable for high-efficient HER. This study provides new insights for designing hierarchical carbon composite nanostructures for catalysts, sensors, energy materials, and other applications.

Ion-Assisted Preparation of Bimetallic Porous Nanodendrites for Active and Stable Water Electrolysis.

Delicate electrochemical active surface area (ECSA) engineering over the exposed catalytic interface and surface topology of platinum-based nanomaterial represents an effective pathway to boost its catalytic properties toward the clean energy conversion system. Here, for the first time, the facial and universal production of dendritic Pt-based nanoalloys (Pt-Ni, Co, Fe) with highly porous feature via a novel Zn2+ -mediated solution approach is demonstrated. In the presence of Zn2+ during synthesis, the competition of different galvanic replacement reactions and consequently generated "branch-to-branch" growth mode are believed to play key roles for the in situ fabrication of such unique nanostructure. Due to the fully exposed active sites and ligand effect-induced electronic optimization, electrochemical hydrogen evolution in alkaline media on these catalysts exhibit dramatic activity enhancement, delivering a current density of 30.6mA cm-2 at a 70mV overpotential for the Pt3 Ni nanodendrites and over 7.4 times higher than that of commercial Pt/C. This work highlights a general and powerful ion-assisted strategy for exploiting dendritic Pt-based nanostructures with efficient activities for water electrolysis.

Electrostatic spray catalytic particle coating on carbon electrode for enhancing electrochemical reaction

The uniform coating of catalytic materials on the electrode surface is essential for improving the performance of electrochemical reactions. In this study, the electrostatic spray coating technique is used to deposit Molybdenum disulfide (MoS2) particles on carbon electrodes and examine the electrochemical hydrogen evolution reaction (HER) performance in a 0.1 M H2SO4 electrolyte. The experimental results reveal that the electrostatic spray coating method achieves a more uniform coating MoS2 catalyst particles on the carbon fiber substrate. It provides good adhesion for electrocatalyst binding on the carbon paper electrodes. During HER analysis, a 25% higher current density is obtained from the electrostatic spray-coated electrodes compared to the manual spray-coated electrode at a potential of 0.95 V. Electrochemical impedance spectroscopy, and electrochemical surface area measurements indicate the superior electrochemical characteristics of the electrostatic spray-coated electrode. The faradaic efficiency of the electrostatic spray-coated electrode is close to 100% at a high applied potential of −1.6 V with a 0.0059 L volume of hydrogen generation. Moreover, chronoamperometric measurements demonstrate the excellent durability of the electrostatic spray-coated carbon electrodes. This study suggests that the facile electrostatic spray method is efficient for coating electrodes with high uniformity and good adhesion for various electrochemical applications.

Effect of different structures on corrosion resistance of Mg–Zn–Ca–Cu alloys

AbstractCompared with traditional magnesium alloys, magnesium‐based metallic glasses exhibit favorable properties, making them potential materials for clinical implants. In this work, to develop magnesium‐based metallic glasses suitable for different degradation requirements, the effects of different structures of Mg–Zn–Ca–Cu alloys on their corrosion resistance were investigated. Mg66Zn29.5Ca4Cu0.5 metallic glasses were prepared by copper mold injection, and the alloys were heat treated at 90°C, 160°C, 230°C, and 270°C. The phase composition was determined by X‐ray diffraction, and electrochemical tests and hydrogen evolution experiments were carried out in a simulated liquid at 37°C. The results show that the corrosion resistance of the alloy is seriously affected by its microstructure.

Ta3N5 Nanobelt-Loaded Ru Nanoparticle Hybrids' Electrocatalysis for Hydrogen Evolution in Alkaline Media.

Electrochemical hydrogen evolution is a highly efficient way to produce hydrogen, but since it is limited by high-cost electrocatalysts, the preparation of high-efficiency electrocatalysts with fewer or free noble metals is important. Here, Ta3N5 nanobelt (NB)-loaded Ru nanoparticle (NP) hybrids with various ratios, including 1~10 wt% Ru/Ta3N5, are constructed to electrocatalyze water splitting for a hydrogen evolution reaction (HER) in alkaline media. The results show that 5 wt% Ru/Ta3N5 NBs have good HER properties with an overpotential of 64.6 mV, a Tafel slope of 84.92 mV/dec at 10 mA/cm2 in 1 M of KOH solution, and good stability. The overpotential of the HER is lower than that of Pt/C (20 wt%) at current densities of 26.3 mA/cm2 or more. The morphologies and structures of the materials are characterized by scanning electron microscopy and high-resolution transmission electron microscopy, respectively. X-ray photoelectron energy spectroscopy (XPS) demonstrates that a good HER performance is generated by the synergistic effect and electronic transfer of Ru to Ta3N5. Our electrochemical analyses and theoretical calculations indicate that Ru/Ta3N5 interfaces play an important role as real active sites.

Effect of Mo2C-functionalized electrode interface on enhancing microbial cathode electrocatalysis: Beyond electrochemical hydrogen evolution

Mo2C has recently been introduced into microbial cathode electrocatalysis due to its well-known catalytic activity for hydrogen evolution reaction (HER), but a low electrode potential (i.e., a high energy input) is required usually. However, in the range of potential where HER cannot occur, its effect on microorganism/cathode interfacial kinetics remains unknown. Herein, an active Mo2C interface is constructed on conventional carbon cloth electrode to investigate its impact on electric-driven fumarate reduction by a typical electroactive microorganism (Shewanella oneidensis MR-1) at a potential of −0.36 V (vs. standard hydrogen electrode) that cannot meet the HER requirement. The Mo2C-functionalized electrode achieves a greatly increased current consumption density of ∼0.041 mA cm−2, about three times that of the control, indicating a faster fumarate reduction rate. This substantially proves that the enhancement of microbial electrocatalytic kinetics at Mo2C-functionalized interface is not confined to the induced hydrogen evolution. By analyzing its interaction with extracellular electron transfer mediators (e.g., c-type cytochromes and riboflavin), a robust inward extracellular electron transfer process based on the rapid electrochemical reaction of riboflavin at the Mo2C-functionalized interface is elaborated. This work provides a new understanding of the mechanism by which the nanostructured Mo2C interface enhances microbial cathode electrocatalysis.