Energy-saving H2 Research Articles

Regulating the electronic structure of Ni3Se4-MoSe2 by coupling with ZIF-derived Co@C promotes boosted urea-assisted water splitting at industrial current density

Adopting urea oxidation reaction (UOR) as an alternative to oxygen evolution reaction (OER) is a prospective approach to achieve energy-saving H2 generation as well as purify wastewater with abundant urea, while the industrial application of bifunctional catalysts for hydrogen evolution reaction (HER) and UOR still remains challenge. Herein, novel coleslaw-like arrays Ni3Se4-MoSe2/Co@C electrocatalyst is fabricated by coupling Ni3Se4-MoSe2 heterointerface with Co-ZIF derived Co@C, in which the synergistic effects of Ni3Se4-MoSe2 and Co@C can tailor the electronic state caused by Ni, Mo, Se and Co atoms, contributing to the modulated d-band center and charge redistribution, hence balancing the absorption and desorption of HER and UOR reaction intermediates and realizing facilitated HER and UOR activities. Furthermore, the coleslaw-like arrays could expose more active sites as well as speed up mass transport. As a result, Ni3Se4-MoSe2/Co@C shows ultralow potentials of 189 mV and 1.427 V to achieve industrial current density of 1000 mA·cm−2 with small Tafel slopes of 56.5 and 30.2 mV·dec-1 towards HER and UOR with exceptional long durability, respectively. Impressively, a remarkably decreased cell voltage of 1.98 V is seen to achieve 1000 mA·cm−2 for urea-assisted water splitting. This study introduces a new strategy to producing non-noble-based selenides with ZIF derivative to realize bifunctional application in energy-saving H2 production with industrial treatment of urea wastewater.

Natural DNA-Derived Ultrafine Ir/Ir2P Hybrid on Porous N, P-Codoped Carbon for pH-Universal Energy-Saving Hydrogen Production Assisted by Electrocatalytic Hydrazine Oxidation

Due to the intrinsic slow kinetics and high potential of the anodic oxygen evolution reaction (OER), hydrazine oxidation reaction (HzOR) with ultralow potential is a viable substitute to combine the cathodic hydrogen evolution reaction (HER) for the energy-saving hydrogen generation. Therefore, it is a compelling demand to explore high-performance electrocatalysts for bifunctional HER and HzOR. Herein, natural DNA was employed to prepare the uniform and ultrafine Ir/Ir2P hybrids loaded on N, P-codoped porous carbon (Ir/PNPC) through a facile “mix-and-pyrolyze” approach. Benefitting from abundant heteroatom doping, large surface area and high degree of graphitization, Ir/PNPC only requires the ultrasmall potentials of -22/-347/-54 mV at 100 mA cm-2 for HER, 46/172/227 mV at 10 mA cm-2 for HzOR, and 167/836/864 mV at 100 mA cm−2 for the constructed two-electrode overall hydrazine splitting (OHzS) in the alkaline, neutral and acidic electrolytes, respectively, all exceeding Pt/C and also showing the remarkable energy-efficient superiority over the conventional water splitting. Furthermore, the OHzS system can be readily driven by the as-prepared direct N2H4/H2O2 fuel cell and commercial solar cell with decent H2 generation rate of 1.245 and 1.392 mmol h-1, respectively. This study provides lights on the preparation of the advanced pH-universal HER and HzOR bifunctional electrocatalysts by natural DNA and is also encouraging for the energy-saving H2 production.

Electrooxidation of glycerol to formic acid coupled with Energy-Saving hydrogen production over ruthenium doped Cobalt-Based nanosheet arrays

The utilization of small molecule oxidation reactions as a substitute for the sluggish oxygen evolution reaction (OER) in traditional water electrolysis represents an innovative approach to achieve efficient hydrogen production while concurrently generating value-added chemicals. Herein, we report an energy-saving H2 production system utilizing electrooxidation of glycerol to generate valuable formate. Cobalt–ruthenium oxide nanosheet arrays (CoRuO/CF) and cobalt–ruthenium bimetallic nanoparticles wrapped by nitrogen-doped carbon nanosheet arrays (CoRuCN/CF) were synthesized for glycerol oxidation reaction (GOR) and hydrogen evolution reaction (HER), respectively, using Co-ZIF nanosheets precursor material supported on copper foam (Co-ZIF/CF) as the substrate. Remarkably, the hybrid electrolysis system can achieve a current density of 10 mA cm−2 with only 1.19 V, which is significantly lower than that required by traditional water-splitting systems. This work demonstrates the promising potential of efficiently utilizing biomass energy and achieving a sustainable production process for fine chemical products.

Engineering p-d orbital hybridization in PdSb bimetallene for energy-saving H2 production parallel upgrade plastic waste

The electrochemical conversion of PET-derived ethylene glycol into high-quality chemicals parallel energy-saving H2 production is an optimal solution to the serious environmental pollution of plastics. In this paper, p-d orbital hybrid PdSb bimetallene with defect-rich crimped surface is synthesized by a one-step solvent approach. PdSb bimetallene exhibits excellent electrocatalytic performance in ethylene glycol and PET hydrolysate oxidation attributed to the unconventional p-d orbital hybridization feature and metallene structure. PdSb bimetallene shows better properties than Pd metallene and commercial Pd black catalysts under ethylene glycol conditions and PET hydrolysate. Besides PdSb bimetallene can oxidize ethylene glycol to produce the valuable product glycolic acid with high Faradaic efficiency and selectivity. Besides, PdSb bimetallene can oxidize PET-derived ethylene glycol into glycolic acid with high selectivity in EGOR||HER system. This study provides insights into the synthesis of metallene with p-d orbital hybridization properties, coupled with energy-saving H2 production parallel upgrade plastic waste.

Defect Engineering of Nickel-Based Compounds for Energy-Saving H2 Production

Defect Engineering of Nickel-Based Compounds for Energy-Saving H2 Production

Pt-decorated spinel MnCo2O4 nanosheets enable ampere-level hydrazine assisted water electrolysis

Coupling hydrazine oxidation reaction (HzOR) with hydrogen evolution reaction (HER) has been widely concerned for high efficiency of green hydrogen preparation with low energy consumption. However, the lacking of bifunctional electrodes with ampere-level performance severely limits its industrialization. Herein, we put forward an efficient active site anchored strategy for MnCo2O4 nanosheet arrays on nickel foam (NF) by introducing Pt species (denoted as Pt-MnCo2O4/NF), which is standing for excellent bifunctional electrodes. The Pt-MnCo2O4/NF delivers ultralow potentials of −195 mV and 350 mV at 1000 mA cm−2 as well as robust stability for HzOR and HER, respectively. The study of in-situ Raman and reaction kinetics reveal that the formation of key adsorbed *NH2 and *N2H4 intermediates and the rapidly oxidization of intermediates with a fast interfacial charge transfer on Pt-MnCo2O4/NF. Remarkably, the Pt-MnCo2O4/NF assembled two-electrode hydrazine assisted water electrolyzer realizes current density of 100 mA cm−2 and 1000 mA cm−2 at 0.16 V and 0.62 V with over 80 h stability. This work provides a promising way to design efficient electrodes for energy-saving H2 generation under ampere-level current density.

Ni-Cu-based phosphide heterojunction for 5-hydroxymethylfurfural electrooxidation-assisted hydrogen production at large current density

5-hydroxymethylfurfural oxidation reaction (HMFOR) offers a promising avenue to achieve energy-saving H2 production and produce value-added chemicals. However, the lack of HMFOR electrocatalysts with large current density and high selectivity impedes the whole productivity. Herein, a Ni3P-Cu3P heterojunction grown on Cu foam (Ni3P-Cu3P/CF) was successfully constructed, achieving large current density (300 mA cm−2 at 1.60 V vs. RHE) and high selectivity and Faradaic efficiency (>99 %) for HMFOR. The X-ray photoelectron spectroscopy and theoretical calculations reveal that the interface charge redistributes at the Ni3P-Cu3P heterointerface, resulting into the charge-deficiency Ni3P and charge-accumulation Cu3P. The charge-deficiency Ni3P induced by charge-attracting Cu3P favors to form more high-valence Ni species, which facilitates to optimize the adsorption of HMF and OH* species for improving current density and decreasing potential, while the charge-accumulation Cu3P enables to broaden the potential window by suppressing competitive oxygen evolution reaction, thus elevating the conversion rate and selectivity of products. Benefiting from the excellent performance of Ni3P-Cu3P/CF for HMFOR, when constructing a HMFOR-assisted H2 production system using Ni3P-Cu3P/CF and self-prepared MoNiNx/NF as anode and cathode, the energy consumption was substantially decreased to 3.8 kW•h/Nm3 relative to that of pure water splitting (4.66 kW•h/Nm3). Our work is instructive for achieving low energy consumption of H2 production and synthesis of valuable chemicals by constructing heterojunction.

Hollow RuV-Co(OH)2 arrays for efficiently electrocatalytic H2 production assisted by glucose oxidation

Electrochemical water splitting is a promising method for hydrogen production but is restricted by sluggish oxygen evolution reaction (OER), so we propose to replace OER with the thermodynamically preferred glucose oxidation reaction (GOR) to reduce the supply voltage. Herein, hollow RuV-Co(OH)2 arrays have been fabricated by the hydrothermal method of sacrificing ZIF-67 to codope vanadium (V) and ruthenium (Ru). Electrochemical studies show that RuV-Co(OH)2 has excellent hydrogen evolution reaction (HER) activity with a low overpotential of 77 mV at the current density of 10 mA cm−2 (η10 = 77 mV) and good GOR activity. Density functional theory (DFT) calculations indicate that V and Ru tune the electronic structure of RuV-Co(OH)2, greatly increasing the density of the active sites. Moreover, RuV-Co(OH)2 assembled glucose-assisted hydrogen evolution cell exhibits a battery voltage of 1.42 V for a current density of 10 mA cm−2, a significant reduction of 240 mV compared to overall water splitting along with higher-value glucose oxidation products. Furthermore, RuV-Co(OH)2 exhibits outstanding stability. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis demonstrate that RuV-Co(OH)2 has superior mechanical stability. This work opens up a new approach to designing novel bifunctional electrocatalysts for energy-saving H2 production and valuable coproductions.

Leveraging phosphate group in Pd/PdO decorated nickel phosphate microflowers via pulsed laser for robust hydrogen production in hydrazine-assisted electrolyzer

By driving the electrooxidation of small molecules instead of relying on sluggish oxygen evolution reaction (OER), low-input voltage is obtained for overall water splitting (OWS) and hydrogen generation, requiring active electrocatalysts. Using single-step pulsed laser irradiation, strong metal-support interaction is achieved on Pd/PdO-decorated Ni3(PO4)2·8H2O (NiPh) microflowers, yielding an outstanding bifunctional electrocatalyst for hydrogen evolution (HER) and hydrazine oxidation (HzOR). When Pd/PdO-NiPh-3 serves as both anode and cathode in the OWS electrolyzer (OER||HER), a cell voltage of 2.098 V achieves 10 mA/cm2 in 1.0 M KOH. When evaluated in the hydrazine-coupled electrolyzer (HzOR||HER), Pd/PdO-NiPh-3 exhibits remarkable stability with a low cell voltage of 0.538 V in 0.5 M-N2H4/1.0 M-KOH, which is approximately 1.56 V lower than that of the traditional water electrolyzers. In Pd/PdO-NiPh, the empty 4s and 5s orbitals of Ni2+ and Pd, respectively, serve as two absorption sites. These sites facilitate chemisorption on the electrocatalyst surface by forming a two-electron dipolar bond between the lone-pair electrons of NH2 groups in N2H4 and Ni2+ as well as Pd. A feasible strategy for utilizing Pd/PdO-NiPh catalysts in developing direct N2H4 fuel cells is investigated in this work, enabling the simultaneous production of robust energy-saving H2 fuel and electricity.

Barium-induced lattice expansion of Ni(OH)2: enhancing catalytic urea oxidation activity for energy-saving H2 production.

Constructing an environmentally friendly and efficient electrocatalyst holds important and profound significance for energy-efficient hydrogen production. Replacing the oxygen evolution reaction with a lower potential urea oxidation reaction (UOR) may save energy in water electrolysis to produce hydrogen. The UOR is characterized by its high energy barrier, which results in slow reaction kinetics. In this study, we introduced Ba(OH)2 into Ni(OH)2 to form uniform nanosheets. Due to the introduction of Ba2+, the lattice expansion of Ni(OH)2 was triggered, leading to significant improvement in UOR activity. The catalyst achieved a current density of 100 mA cm-2 at only 1.316 V and exhibited remarkable stability over time. Density functional theory (DFT) calculations demonstrate that the Ba-Ni(OH)2 site significantly reduces the energy barrier for urea adsorption, intermediate steps, and desorption. This work provides a novel and environmentally friendly strategy for constructing energy-efficient and highly efficient catalysts through the doping of alkaline earth metals.

Enhanced surface reconstruction of V-doped Ni3N driven by strong OH adsorption to boost 5-hydroxymethylfurfural electrooxidation for energy-saving H2 production

The 5%V-Ni3N exhibits high efficiency for the 5-hydroxymethylfurfural oxidation reaction for boosting energy-saving H2 production. The doped V could strengthen the OH adsorption for enhancing the surface reconstruction to active (oxy)hydroxide sites.

Iodide-assisted energy-saving hydrogen production using self-supported sulfate ion-modified NiFe(oxy)hydroxide nanosheets.

Hybrid water electrolysis (HyWES) with iodide oxidation as non-OER for energy-saving H2 production is demonstrated using self-supported sulfate ion modified Ni,Fe(oxy)hydroxide as the anode. The sulfate ions adsorbed on the catalyst show a promoting effect in achieving high electrochemical activity. The HyWES requires a voltage as low as 1.36 V to achieve the bechmark current density of 10 mA cm-2.

Local-reconstruction enables cobalt phosphide array with bifunctional hydrogen evolution and hydrazine oxidation

Coupling hydrazine electrooxidation with hydrogen evolution reaction (HER) attracts ever-growing attention for energy-saving H2 production. However, the performance of hydrazine-assisted HER unit is restricted by the bifunctional catalysts with un-fully activated sites. Herein, a surface local-reconstruction strategy is proposed to integrate amorphous Co(OH)2 and P vacant CoP into the CoH-CoPV@CFP catalyst. The inherent electron-deficient Co sites in Co(OH)2 show strong N-Co interaction to accelerate the N2H4 dehydrogenation kinetics, while the as-formed P vacancies in CoP play a crucial role in moderating the H* adsorption energy, the excellent bifunctionality thus being obtained. Specifically, it achieves the low overpotentials of − 77 and − 61 mV at 10 mA cm−2 for HER and HzOR in alkaline media, respectively. A lab-scale electrolyzer can deliver the industrial-grade current density of 500 mA cm−2 under ultralow cell voltage of 0.23 V. This local-reconstruction strategy may pave new avenue to design efficient catalysts for hydrazine-assisted H2 generation.

Capturing critical gem-diol intermediates and hydride transfer for anodic hydrogen production from 5-hydroxymethylfurfural

The non-classical anodic H2 production from 5-hydroxymethylfurfural (HMF) is very appealing for energy-saving H2 production with value-added chemical conversion due to the low working potential (~0.1 V vs RHE). However, the reaction mechanism is still not clear due to the lack of direct evidence for the critical intermediates. Herein, the detailed mechanisms are explored in-depth using in situ Raman and Infrared spectroscopy, isotope tracking, and density functional theory calculations. The HMF is observed to form two unique inter-convertible gem-diol intermediates in an alkaline medium: 5-(Dihydroxymethyl)furan-2-methanol anion (DHMFM−) and dianion (DHMFM2−). The DHMFM2− is easily oxidized to produce H2 via H− transfer, whereas the DHMFM− is readily oxidized to produce H2O via H+ transfer. The increases in potential considerably facilitate the DHMFM− oxidation rate, shifting the DHMFM− ↔ DHMFM2− equilibrium towards DHMFM− and therefore diminishing anodic H2 production until it terminates. This work captures the critical intermediate DHMFM2− leading to hydrogen production from aldehyde, unraveling a key point for designing higher performing systems.

Highly enhanced bifunctionality by trace Co doping into Ru matrix towards hydrazine oxidation-assisted energy-saving hydrogen production

As an alternative to oxygen evolution reaction (OER), the low-potential hydrazine oxidation reaction (HzOR) can assemble with hydrogen evolution reaction (HER) to fulfill the energy-saving H2 generation, which demands of developing high-quality bifunctional electrocatalysts for HER and HzOR. Herein, a simple one-pot wet-chemical method was employed to facilely prepared the highly dispersed RuCo alloy particles onto oxygenated carbon black (RuCo/C). With the trace doping of Co into Ru matrix, RuCo/C exhibits the significantly boosted bifunctional activity, superior to the recently reported counterparts, with low potentials of –13.3 and –76.8 mV at 10 mA·cm−2 for HER and HzOR, respectively. Additionally, the novel HER||HzOR electrolysis system just requires a small voltage of 215.4 mV at 100 mA·cm−2, and thus is easily operated under low-energy portable external powers (fuel cell and solar cell) with impressive H2 production, demonstrating the superiority in energy saving and convenient operation. Moreover, theoretical calculations unclose upon alloying with trace Co, the H2O dissociation energy barrier and hydrogen ad/desorption of HER can be simultaneously optimized on Ru active sites, and the rate-determining energy barrier of HzOR can be also greatly reduced. This study provides one simple but workable approach to prepare high-performance bifunctional HER and HzOR eletrocatalysts, highly promising for the energy-saving H2 production.

Self-Powered Hydrogen Production with Improved Energy Efficiency via Polysulfides Redox.

In the pursuit of efficient solar-driven electrocatalytic water splitting for hydrogen production, the intrinsic challenges posed by the sluggish kinetics of anodic oxygen evolution and intermittent sunlight have prompted the need for innovative energy systems. Here, we introduce an approach by coupling the polysulfides oxidation reaction with the hydrogen evolution reaction for energy-saving H2 production, which could be powered by an aqueous zinc-polysulfides battery to construct a self-powered energy system. This unusual hybrid water electrolyzer achieves 300 mA cm-2 at a low cell voltage of 1.14 V, saving electricity consumption by 100.4% from 5.47 to 2.73 kWh per m3 H2 compared to traditional overall water splitting. Benefiting from the favorable reaction kinetics of polysulfides oxidation/reduction, the aqueous zinc-polysulfides battery exhibits an energy efficiency of approximately 89% at 1.0 mA cm-2. Specially, the zinc-polysulfide battery effectively stores intermittent solar energy as chemical energy during light reaction by solar cells. Under an unassisted light reaction, the batteries could release energy to drive H2 production through a hybrid water electrolyzer for uninterrupted hydrogen production. Therefore, the aim of simultaneously generating H2 and eliminating the restrictions of intermittent sunlight is realized by combining the merits of polysulfides redox, an aqueous metal-polysulfide battery, and solar cells. We believe that this concept and utilization of polysulfides redox will inspire further fascinating attempts for the development of sustainable energy via electrocatalytic reactions.

Enhanced hydrogen production via urea electrolysis over Ni-NiO electrodeposited on Ti mesh

The sluggish kinetics of anodic oxygen evolution reaction (OER) is regarded as the main bottleneck for ineffective hydrogen production efficiency, limiting the industrial application of electrochemical water splitting. Substituting the OER by urea electrooxidation reaction (UOR) and simultaneously developing highly active and economical bifunctional electrocatalyst for UOR and hydrogen evolution reaction (HER) is a promising method to realize energy-saving hydrogen production and urea-rich wastewater abatement. Herein, self-supporting Ni-NiO film grown on Ti mesh (Ni-NiO/TM) was successfully prepared by a facile cathodic electrodeposition method with using nickel acetate as the only raw material. Electrodeposition process was optimized by modulating the electrodeposition time and potential. x-ray diffraction, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and Raman characterization revealed the optimized Ni-NiO/TM was comprised of crystalline Ni and amorphous NiO and its morphology exhibited nanosphere structure, assembled by nanosheets. Ni-NiO/TM sample prepared under the potential of −1.5 V and deposition time of 10 min illustrated the lowest UOR potential of 1.34 V at 50 mA cm−2 and robust stability, superior to the recently reported literatures. Furthermore, the HER potential was only −0.235 V to drive the current density of 50 mA cm−2. The cell voltage of urea-assisted electrolysis for hydrogen production in Ni-NiO/TM||Ni-NiO/TM two-electrode system only required 1.56 V to deliver 50 mA cm−2, obviously lower than that (>1.72 V) for overall water splitting. This work demonstrated the potential of Ni-based material as bifunctional electrocatalyst for energy-saving H2 production by urea-rich wastewater electrolysis.

Bifunctional Al-Doped Cobalt Ferrocyanide Nanocube Array for Energy-Saving Hydrogen Production via Urea Electrolysis.

The very slow anodic oxygen evolution reaction (OER) greatly limits the development of large-scale hydrogen production via water electrolysis. By replacing OER with an easier urea oxidation reaction (UOR), developing an HER/UOR coupling electrolysis system for hydrogen production could save a significant amount of energy and money. An Al-doped cobalt ferrocyanide (Al-Co2Fe(CN)6) nanocube array was in situ grown on nickel foam (Al-Co2Fe(CN)6/NF). Due to the unique nanocube array structure and regulated electronic structure of Al-Co2Fe(CN)6, the as-prepared Al-Co2Fe(CN)6/NF electrode exhibited outstanding catalytic activities and long-term stability to both UOR and HER. The Al-Co2Fe(CN)6/NF electrode needed potentials of 0.169 V and 1.118 V (vs. a reversible hydrogen electrode) to drive 10 mA cm-2 for HER and UOR, respectively, in alkaline conditions. Applying the Al-Co2Fe(CN)6/NF to a whole-urea electrolysis system, 10 mA cm-2 was achieved at a cell voltage of 1.357 V, which saved 11.2% electricity energy compared to that of traditional water splitting. Density functional theory calculations demonstrated that the boosted UOR activity comes from Co sites with Al-doped electronic environments. This promoted and balanced the adsorption/desorption of the main intermediates in the UOR process. This work indicates that Co-based materials as efficient catalysts have great prospects for application in urea electrolysis systems and are expected to achieve low-cost and energy-saving H2 production.

Significantly Enhanced Energy-Saving H2 Production Coupled with Urea Oxidation by Low- and Non-Pt Anchored on NiS-Based Conductive Nanofibers.

Rational designing electrocatalysts is of great significance for realizing high-efficiency H2 production in the water splitting process. Generally, reducing the usage of precious metals and developing low-potential nucleophiles oxidation reaction to replace anodic oxygen evolution reaction (OER) are efficient strategies to promote H2 generation. Here, NiS-coated nickel-carbon nanofibers (NiS@Ni-CNFs) are prepared for low-content Pt deposition (Pt-NiS@Ni-CNFs) to attain the alkaline HER catalyst. Due to the reconfiguration of NiS phase and synergistic effect between Pt and nickel sulfides, the Pt-NiS@Ni-CNFs catalyst shows a high mass activity of 2.74-fold of benchmark Pt/C sample. In addition, the NiS@Ni-CNFs catalyst performs a superior urea oxidation reaction (UOR) activity with the potential of 1.366V versus reversible hydrogen electrode (RHE) at 10mA cm-2 , which demonstrates the great potential in the replacement of OER. Thus, a urea-assisted water splitting electrolyzer of Pt-NiS@Ni-CNFs (cathode)||NiS@Ni-CNFs (anode) is constructed to exhibit small voltages of 1.44 and 1.65V to reach 10 and 100mA cm-2 , which is much lower than its overall water splitting process, and presents a 6.5-fold hydrogen production rate enhancement. This work offers great opportunity to design new catalysts toward urea-assisted water splitting with significantly promoted hydrogen productivity and reduced energy consumption.

Identifying And Unveiling the Role of Multivalent Metal States for Bidirectional UOR and HER Over Ni, Mo-Trithiocyanuric Based Coordination Polymer.

Urea oxidation reaction (UOR), an ideal alternative to oxygen evolution reaction (OER), has received increasing attention for realizing energy-saving H2 production and relieving pollutant degradation. Normally, most studied Ni-based UOR catalysts pre-oxidate to NiOOH and then act as active sites. However, the unpredictable transformation of the catalyst's structure and its dissolution and leaching, may complicate the accuracy of mechanism studies and limit its further applications. Herein, a novel self-supported bimetallic Mo-Ni-C3 N3 S3 coordination polymers (Mo-NT@NF) with strong metal-ligand interactions and different H2 O/urea adsorption energy are prepared, which realize a bidirectional UOR/hydrogen evolution reaction (HER) reaction pathway. A series of Mo-NT@NF is prepared through a one-step mild solvothermal method and their multivalent metal states and HER/UOR performance relationship is evaluated. Combining catalytic kinetics, in situ electrochemical spectroscopic characterization, and density-functional theory (DFT) calculations, a bidirectional catalytic pathway is proposed by N, S-anchored Mo5+ and reconstruction-free Ni3+ sites for catalytic active center of HER and UOR, respectively. The effective anchoring of the metal sites and the fast transfer of the intermediate H* by N and S in the ligand C3 N3 S3 H3 further contribute to the fast kinetic catalysis. Ultimately, the coupled HER||UOR system with Mo-NT@NF as the electrodes can achieve energy-efficient overall-urea electrolysis for H2 production.