Energy-efficient Hydrogen Production Research Articles

Effect of multi-interface electron transportation and molecule adsorption on hydrogen evolution reaction

The widespread industrial application of water electrolysis to hydrogen production is limited by its high cost, high energy consumption and low conversion efficiency. This work demonstrates the energy-efficient hydrogen production can be attained by the rational design of electrolyser with efficient electrocatalyst. Typically, the efficient CoP3-FeOOH-Ni2P-C3N4 (CoFeNiC) electrocatalyst is prepared by calcining the mixture of both ZIF-67 and NiFe-LDH, which exhibits a good electrolysis performance in an alkaline electrolyte. At 10 mA cm−2, the oxygen evolution reaction (OER) overpotential of CoFeNiC (146 mV) is lower than the previously reported results, and the Faraday efficiency (FE) reaches 94.8 %. In addition, density functional theory (DFT) calculations demonstrate that the large work function difference between FeOOH, Ni2P and C3N4 is beneficial to form stable hetero-interface, which significantly optimize the interface electronic structure and enhances the electron transfer from FeOOH, Ni2P to C3N4; and CoP3 has a strong molecule adsorption ability. Thereby CoFeNiC shows an enhaned water-splitting efficiency. Moreover, an asymmetric electrolyzer is constructed by using CoFeNiC as cathode and NiFe-LDH as anode. At 150 mA cm−2, the cell voltage of CoFeNiC//NiFe-LDH electrolyzer decreases by 11.67 %, compared with symmetric NiFe-LDH electrolyzer. The i-t test shows that the asymmetrical electrolyzer exhibits a good stability at a high current density.

Activating Interfacial Electron Redistribution in Lattice-Matched Biphasic Ni3N-Co3N for Energy-Efficient Electrocatalytic Hydrogen Production via Coupled Hydrazine Degradation.

The development of high-purity and high-energy-density green hydrogen through water electrolysis holds immense promise, but issues such as electrocatalyst costs and power consumption have hampered its practical application. In this study, we present a promising solution to these challenges through the use of a high-performance bifunctional electrocatalyst for energy-efficient hydrogen production via coupled hydrazine degradation. The biphasic metal nitrides with highly lattice-matched structures are deliberately constructed, forming an enhanced local electric field between the electron-rich Ni3N and electron-deficient Co3N. Additionally, Mn is introduced as an electric field engine to further activate electron redistribution. Our Mn@Ni3N-Co3N/NF bifunctional electrocatalyst achieves industrial-grade current densities of 500 mA cm-2 at 0.49 V without degradation, saving at least 53.3 % energy consumption compared to conventional alkaline water electrolysis. This work will stimulate the further development of metal nitride electrocatalysts and also provide new perspectives on low-cost hydrogen production and environmental protection.

Metallic Cu-incorporated NiFe layered double hydroxide nanosheets enabling energy-saving hydrogen generation from chlorine-free seawater electrolysis coupled with sulfion upcycling

Development of multifunctional non-noble electrocatalysts for seawater electrolysis is imperative but still challenging for scale-up hydrogen production to avoid harmful chlorine chemistry. Herein, the metallic Cu-incorporated NiFe layered double hydroxide (LDH) nanosheets are prepared by a facile consecutive corrosion strategy using iron foam (IF) as a reactive substrate, which enable the corrosion-resistant and chlorine-free seawater electrolysis combined with anodic sulfion oxidation for energy-efficient hydrogen production at ultralow electricity consumption. The NiFe-LDH/Cu-IF exhibits excellent electrocatalytic activities for hydrogen evolution reaction (HER) and sulfion oxidation reaction (SOR), achieving low potentials of 0.203 and 0.310 V (vs RHE) at 100 mA cm−2 in alkaline seawater, respectively. The assembled hybrid HER||SOR seawater electrolyzer realizes the ultra-low cell voltage of 0.619 V and power consumption of 1.48 kWh/m3 H2 at 50 mA cm−2, cutting energy consumption over 67 % compared to conventional seawater electrolysis.

Self-Limited Formation of Cobalt Nanoparticles for Spontaneous Hydrogen Production through Hydrazine Electrooxidation.

Hydrogen (H2 ) has emerged as a highly promising energy carrier owing to its remarkable energy density and carbon emission-free properties. However, the widespread application of H2 fuel has been limited by the difficulty of storage. In this work, spontaneous electrochemical hydrogen production is demonstrated using hydrazine (N2 H4 ) as a liquid hydrogen storage medium and enabled by a highly active Co catalyst for hydrazine electrooxidation reaction (HzOR). The HzOR electrocatalyst is developed by a self-limited growth of Co nanoparticles from a Co-based zeolitic imidazolate framework (ZIF), exhibiting abundant defective surface atoms as active sites for HzOR. Notably, these self-limited Co nanoparticles exhibit remarkable HzOR activity with a negative working potential of -0.1V (at 10mA cm-2 ) in 0.1m N2 H4 /1m KOH electrolyte. Density functional theory (DFT) calculations are employed to validate the superior performance of low-coordinated Co active sites in facilitating HzOR. By taking advantage of the potential difference between HzOR and the hydrogen evolution reaction (HER), a novel HzOR||HER electrochemical system is developed to spontaneously produce H2 without external energy input. Overall, the work offers valuable guidance for developing active HzOR catalyst. The novel HzOR||HER electrochemical system represents a promising and innovative solution for energy-efficient hydrogen production.

B doped cobalt-nickel bimetallic phosphide as bifunctional catalyst for ethanol oxidation reaction and hydrogen evolution reaction

The ethanol oxidation reaction (EOR) is an ideal alternative to the oxygen evolution reaction (OER) towards energy efficient hydrogen production. Here, the chrysanthemum-shaped B doped cobalt-nickel bimetallic phosphide with heterogeneous structure grown on nickel foam (B-Ni2P/CoP/NF) are synthesized and can act as a high activity bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and EOR. In 1.0 M KOH, the obtained catalyst shows good activity and excellent long-term stability (no decay after 108 h) for HER, with an overpotential of only 33 mV (vs. RHE) to reach a current density of 10 mA cm−2. The calculation of turnover frequency (TOF) and transfer coefficient (β) prove that the catalyst has good intrinsic catalytic activity, For EOR, in 1.0 M KOH+1.0 M C2H5OH solution, the B-Ni2P/CoP/NF catalyst requires only 1.45 V (vs. RHE) oxidation potential to reach the current density of 50 mA cm−2, which is 270 mV less than OER. Using B-Ni2P/CoP/NF as a bifunctional catalyst, the current density of 20 mA cm−2 can be achieved with only 1.48 V cell voltage in 1.0 M KOH+ 1.0 M C2H5OH solution, which is remarkably lower than the required cell voltage of water electrolysis (1.63 V) to achieve the same current density. This study demonstrates an efficient bimetallic phosphide as earth-abundant bifunctional electrocatalysts for green hydrogen production coupled with electrolysis of ethanol.

An energy-efficient H2 production based on urea-aided water splitting enhanced by Ru induced in-situ speciation of NiO nanosheets on porous Ni

Efficient hydrogen production by water electrolysis is primarily restrained by imperfect over-potential and poor reaction dynamics on oxygen evolution reaction (OER). Thermodynamically favourable urea oxidation reaction (UOR) is a class of promising routes for substituting sluggish OER and for coupling with cathodic hydrogen production because of smaller equilibrium potential (0.37 V) than that of OER (1.23 V). Herein, a versatile Ru-NiO/p-Ni catalyst was prepared through in-situ generating nickel hydroxide nanosheets on the surface of ordered porous Ni, then doping low Ru and annealing treatment. The optimized Ru-NiO/p-Ni displayed outstanding activity and stability towards hydrogen evolution reaction (HER), OER and UOR with potentials of −0.13 V, 1.57 V, and 1.39 V at 100 mA cm−2, respectively. Ru-NiO/p-Ni‖Ru-NiO/p-Ni can achieve 100 mA cm−2 in urea-aided water splitting at a voltage of only 1.58 V, which is prominently 170 mV smaller than the voltage of water electrolysis (1.75 V). The excellent electrocatalytic performance is owing to the outstanding inherent activity generated by cooperative effect of Ru and NiO, along with rich defect and active centre of Ru-NiO/p-Ni supplied by the large surface area of 3D porous structure. The formation of more rich Ni active species with a high valence through transport of electrons between Ru and Ni is favourable to promoting the dissociation of urea molecules, eventually improving UOR. Therefore, it can facilitate urea-aided water splitting, which provides a valuable strategy for constructing versatile catalysts for a cathodic energy-efficient hydrogen production coupled with other anodic oxidation reactions.

Self-supported ultrathin NiMn-LDH nanosheets for highly active and robust urea oxidation

Due to its low equilibrium potential, urea oxidation reaction (UOR) is an advantageous alternative to the conventional anodic water oxidation reaction (OER) for energy-saving hydrogen production. Developing energy- and time-saving methods to synthesize active and stable UOR catalysts is significant. Herein, we present a simple and time-efficient method for the direct growth of defect-rich few-layered NiMn-layered double hydroxide (NiMn-LDH) nanosheets on nickel foam at ambient temperature and pressure. The defect-rich, few-layered structure exposes numerous active sites, promoting the formation of high-oxidation state Ni species at low overpotentials. Additionally, the introduction of Mn facilitates Ni oxidation and stabilizes in-situ formed NiOOH species. The optimized f-NiMn-LDH catalyst exhibits compelling UOR activity, requiring only 1.310/1.330/1.387 V for 10/100/400 mA cm−2 UOR, respectively. When used directly in urea-assisted hydrogen production, it achieves a low cell voltage of 1.436 V for a high current density of 100 mA cm−2, representing a substantial 249 mV reduction compared to water electrolysis. This work offers a simple strategy for preparing high-performance electrocatalysts for energy-efficient hydrogen production via urea-assisted water splitting.

In Situ Assembly of a Superaerophobic CoMn/CuNiP Heterostructure as a Trifunctional Electrocatalyst for Ampere-Level Current Density Urea-Assisted Hydrogen Production.

Urea electrolysis is a promising energy-efficient hydrogen production process with environmental benefits, but the lack of efficient and sustainable ampere-level current density electrocatalysts fabricated through simple methods is a major challenge for commercialization. Herein, we present an efficient and stable heterostructure electrocatalyst for full urea and water electrolysis in a convenient and time-efficient preparation manner. Overall, superhydrophilic/superaerophobic CoMn/CuNiP/NF exhibits exceptional performance for the hydrogen evolution reaction (HER) (-33.8, -184.4, and -234.8 mV at -10, -500, and -1000 mA cm-2, respectively), urea electro-oxidation reaction (UOR) [1.28, 1.43, and 1.51 V (vs RHE) at 10, 500, and 1000 mA cm-2, respectively], and oxygen evolution reaction (OER) [1.45, 1.67, and 1.74 V (vs RHE) at 10, 500, and 1000 mA cm-2, respectively]. Moreover, the superaerophobic CoMn/CuNiP/NF demonstrates promising potential in full urea (1.33, 1.57, and 1.60 V at 10, 500, and 1000 mA cm-2, respectively) and water (1.46 V, 1.78, and 1.86 at 10, 500, and 1000 mA cm-2, respectively) electrolysis. Based on X-ray photoelectron spectroscopy results, it was determined that the surface of the CoMn/CuNiP electrode was rich in redox pairs such as Ni2+/Ni3+, Cu+/Cu2+, Co2+/Co3+, and Mn2+/Mn3+, which are crucial for the formation of active sites for the OER and UOR, such as NiOOH, MnOOH, and CoOOH, thereby enhancing the catalytic activity. Besides, the in situ assembled CoMn/CuNiP/NF displayed highly stable performance for HER, OER, and UOR with high Faradaic efficiency for over 500 h. This research offers a simple and efficient method for manufacturing a high-efficiency and stable trifunctional electrocatalyst capable of delivering ampere-level current density in urea-assisted hydrogen production. Our density functional theory calculations reveal the potential of CoMn/CuNiP as an effective catalyst, enhancing the electronic properties and catalytic performance. The near-zero Gibbs free-energy change for HER underscores its promise, while reduced CO2 desorption energies and charge redistribution support efficient UOR. These findings signify CoMn/CuNiP's potential for electrochemical applications.

Heterojunction-Induced Rapid Transformation of Ni3+ /Ni2+ Sites which Mediates Urea Oxidation for Energy-Efficient Hydrogen Production.

Water electrolysis is an environmentally-friendly strategy for hydrogen production but suffers from significant energy consumption. Substituting urea oxidation reaction (UOR) with lower theoretical voltage for water oxidation reaction adopting nickel-based electrocatalysts engenders reduced energy consumption for hydrogen production. The main obstacle remains strong interaction between accumulated Ni3+ and *COO in the conventional Ni3+ -catalyzing pathway. Herein, a novel Ni3+ /Ni2+ mediated pathway for UOR via constructing a heterojunction of nickel metaphosphate and nickel telluride (Ni2 P4 O12 /NiTe), which efficiently lowers the energy barrier of UOR and avoids the accumulation of Ni3+ and excessive adsorption of *COO on the electrocatalysts, is developed. As a result, Ni2 P4 O12 /NiTe demonstrates an exceptionally low potential of 1.313V to achieve a current density of 10mA cm-2 toward efficient urea oxidation reaction while simultaneously showcases an overpotential of merely 24mV at 10mA cm-2 for hydrogen evolution reaction. Constructing urea electrolysis electrolyzer using Ni2 P4 O12 /NiTe at both sides attains 100mA cm-2 at a low cell voltage of 1.475V along with excellent stability over 500 h accompanied with nearly 100% Faradic efficiency.

Green electrosynthesis of 3,3’-diamino-4,4’-azofurazan energetic materials coupled with energy-efficient hydrogen production over Pt-based catalysts

The broad employment of clean hydrogen through water electrolysis is restricted by large voltage requirement and energy consumption because of the sluggish anodic oxygen evolution reaction. Here we demonstrate a novel alternative oxidation reaction of green electrosynthesis of valuable 3,3’-diamino-4,4’-azofurazan energetic materials and coupled with hydrogen production. Such a strategy could greatly decrease the hazard from the traditional synthetic condition of 3,3’-diamino-4,4’-azofurazan and achieve low-cell-voltage hydrogen production on WS2/Pt single-atom/nanoparticle catalyst. The assembled two-electrode electrolyzer could reach 10 and 100 mA cm–2 with ultralow cell voltages of 1.26 and 1.55 V and electricity consumption of only 3.01 and 3.70 kWh per m3 of H2 in contrast of the conventional water electrolysis (~5 kWh per m3). Density functional theory calculations combine with experimental design decipher the synergistic effect in WS2/Pt for promoting Volmer–Tafel kinetic rate during alkaline hydrogen evolution reaction, while the oxidative-coupling of starting materials driven by free radical could be the underlying mechanism during the synthesis of 3,3’-diamino-4,4’-azofurazan. This work provides a promising avenue for the concurrent electrosynthesis of energetic materials and low-energy-consumption hydrogen production.

The Ni–P dual vacancies crystalline/amorphous bifunctional electrode with ZnO “electron pump” for urea-assisted electrolysis of water to produce hydrogen

Electrochemical urea electrolysis holds great potential for energy-efficient hydrogen production and wastewater treatment. However, developing cost-effective and highly active catalysts remains a challenge. In this study, a novel bifunctional electrocatalyst of Ni–Zn bimetallic nanosheets (ZnO–Ni2P) was synthesized on Ni foam (NF) for efficient urea decomposition in urea-containing wastewater. The results showed that inactive ZnO phase acted as an "electron pump", which facilitated electron redistribution between Ni and P atoms and created localized vacancies of Ni and P cations. This optimized electronic configuration enhanced the kinetics of both the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Additionally, a unique particle-porous structure with abundant grain boundaries was achieved through the utilization of the Kirkendall Effect and Ostwald Ripening. In an alkaline urea electrolysis system, the alkaline urea electrolyzer assembled with ZnO–Ni2P/NF sample as both electrodes exhibited a low driving potential of only 1.424 V to achieve a current density of 10 mA cm−2, which outperformed the commercial noble metal-based electrolyzer (RuO2||Pt/C). The results verify that incorporating an inactive phase to manipulate the electronic structure of the active phase can be an effective strategy in developing catalysts for urea electrolysis.

Heterostructured FeP4/CoP@NF as trifunctional electrocatalysts for energy-efficient hydrogen production

The developing of efficient and cost-effective electrocatalysts for hydrogen evolution is of great significance to the development of hydrogen energy. It is believed that the efficient hydrogen generation of water cracking is restricted from the slow oxygen evolution reaction (OER) process. Consequently, it is highly recommended to find alternative anodizing to produce hydrogen to reduce electricity consumption. Urea oxidation reaction (UOR) is an alternative to the traditional anodic OER. In this paper, an electrocatalyst FeP4/CoP@NF-7.5 supported on nickel foam (NF) was designed by using a template-directed growth and low-temperature phosphating method. The FeP4/CoP@NF-7.5 with a rich interface gives it more active sites and enhances mass transfer and conductivity, possessing excellent catalytic performance against hydrogen evolution reaction (HER), OER and UOR in alkaline electrolyte. Thanks to the abundant interface and bimetallic synergy, the designed catalyst exhibits the overpotentials of 45 mV and 259 mV for HER and OER to transfer 10 mA cm−2. In addition, FeP4/CoP@NF-7.5 also possesses significant catalytic activity against UOR of 136 mV (j10) in 1 M KOH with 0.33 M urea, which provides another alternative to the low efficiency of OER through the reduction of hydrogen production costs. Finally, the overall water splitting test was undertaken in 1 M KOH containing/free of 0.33 M urea. Remarkably, only 1.43 V is required to drive on urea electrolyzer (j10 = 10 mA cm−2), while 1.52 V are gained on water electrolyzer. This paper lays the foundation for the developing of high-active transition bimetallic phosphide electrocatalysts for energy-saving hydrogen production.

Highly enhanced hydrazine oxidation on bifunctional Ni tailored by alloying for energy-efficient hydrogen production

The low-potential hydrazine oxidation reaction (HzOR) can replace the oxygen evolution reaction (OER) and thus assemble with the hydrogen evolution reaction (HER), consequently achieving energy-saving hydrogen (H2) production. Notably, developing sophisticated bifunctional electrocatalysts for HER and HzOR is a prerequisite for efficient H2 production. Alloying noble metals with eligible non-precious ones can increase affordability, catalytic activity, and stability, alongside rendering bifunctionality. Herein, RuNi alloy deposited onto carbon (RuNi/C) was directly prepared by a simple and highly practical co-reduction method, showing excellent performance for HER and HzOR. Interestingly, to achieve 10 mA cm−2, RuNi/C only required an ultralow potential of 24 mV for HER, on par with commercial 20 wt% platinum in carbon (Pt/C), and −65 mV for HzOR, surpassing most reported counterparts. Moreover, the two-electrode electrolyzer only required small operation voltages of 57.8 and 327 mV to drive 10 and 100 mA cm−2, respectively. Driven by a homemade hydrazine (N2H4) fuel cell and solar panel, appreciable H2 yields of 1.027 and 1.406 mmol h−1 were achieved, respectively, exhibiting the energy-saving advantages alongside robust practicability. Moreover, theoretical calculations revealed that alloying with Ru endows bifunctional Ni sites not only with a lower H2O dissociation barrier but also with more favorable H* adsorption alongside the reduced energy barrier between HzOR intermediates.

One-Step Electrosynthesis of Bifunctional NiCu Nanosheets on Iron Foam for Remarkably Enhanced Alkaline Water Splitting

Electrocatalytic water splitting for hydrogen production driven by renewable electricity offers a promising way of achieving energy sustainability, but the design of highly efficient and cost-effective electrocatalysts is regarded as a bottleneck. Herein, a bifunctional microflowers NiCu is successfully deposited on an iron foam (IF) electrode via one-step electrolysis of spend cupronickel (SCN). Unexpectedly, the designed IF-supported NiCu (NiCu/IF) electrocatalysts exhibit excellent catalytic performance for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) in 1 M KOH. Only 98 and 267 mV are required to drive a current density of 10 mA cm−2 for HER and OER, respectively. Importantly, the self-supported NiCu/IF electrode requires a low cell voltage of 1.57 V to achieve 10 mA cm−2 of alkaline overall water splitting with extremely high stability. With the introduction of a glycerol oxidation reaction (GOR), the HER performance is further remarkably enhanced with an extremely low cell voltage of 1.29 V at 10 mA cem−2, highlighting an attractive energy-efficient hydrogen production coupled with biomass conversion process. This study reports a novel synthesis strategy for low-cost and high-performance Ni-based nanostructure catalysts using SCN as precursors, which is of vital significance for green hydrogen production and waste recycling.

Controlled Fabrication of Hierarchically Structured MnO2@NiCo-LDH Nanoarrays for Efficient Electrocatalytic Urea Oxidization.

Urea, a prevalent component found in wastewater, shows great promise as a substrate for energy-efficient hydrogen production by electrolysis. However, the slow kinetics of the anodic urea oxidation reaction (UOR) significantly hamper the overall reaction rate. This study presents the design and controlled fabrication of hierarchically structured nanomaterials as potential catalysts for UOR. The prepared MnO2@NiCo-LDH hybrid catalyst demonstrates remarkable improvements in reaction kinetics, benefiting from synergistic enhancements in charge transfer and efficient mass transport facilitated by its unique hierarchical architecture. Notably, the catalyst exhibits an exceptionally low onset potential of 1.228 V and requires only 1.326 V to achieve an impressive current density of 100 mA cm-2, representing a state-of-the-art performance in UORs. These findings highlight the tremendous potential of this innovative material designing strategy to drive advancements in electrocatalytic processes.

Hydrophilic functionalization of rhodium metallene for saving-energy hydrogen production and sulfur recovery

The use of thermodynamically more favorable sulfion oxidation reaction (SOR) to replace sluggish oxygen evolution reaction is an effective method for energy-saving production of hydrogen. Herein, we propose the synthesis of organic–inorganic hybrid through the modification of 1-hydroxyethylidene-1,1-diphosphonic acid on Rh metallene (HEDP-Rh metallene) as a bifunctional electrocatalyst for hydrogen evolution reaction (HER) and SOR. The modification of hydrophilic HEDP can effectively promote the water adsorption, thereby accelerating the mass/electron transfer at the interface. The HEDP-Rh metallene requires low overpotentials of 30 mV at 10 mA cm−2 for HER and 0.538 V at 100 mA cm−2 for SOR. In HER-SOR coupled reaction, HEDP-Rh metallene drives the current density of 100 mA cm−2 at 1.08 V for concurrent production of hydrogen and sulfur, highlighting energy-efficient hydrogen production and sulfur recycle.

Low-content Pt-triggered the optimized d-band center of Rh metallene for energy-saving hydrogen production coupled with hydrazine degradation

Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene (Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen (H2) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization. Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of −10 mA cm−2 in the hydrogen evolution reaction (HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm−2 in the hydrazine oxidation reaction (HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage (0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm−2 for energy-saving H2 production, which greatly reduces the electrolysis energy consumption. Moreover, DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.

Bifunctional Cobalt–Nickel Sulfide Nanoflowers as Electrocatalysts for Concurrent Energy-Efficient Hydrogen Production and Sulfur Recycling

Electrocatalytic water splitting is an important approach for sustainable and green production of hydrogen but is greatly hampered by the sluggish oxygen evolution reaction (OER). Therefore, developing a favorable alternative reaction to replace OER for both energy-efficient coproduction of hydrogen and value-added chemicals is highly desirable. Herein, a thermodynamically favorable sulfion oxidation reaction (SOR) electrocatalyzed by CoNi2S4 nanoflowers (CoNi2S4 NFs) is reported to couple with the hydrogen evolution reaction (HER) for energy-efficient hydrogen production and sulfur recovery. In this coupled system, only a low cell voltage of 0.3 V is required to produce hydrogen at 10 mA cm–2, much lower than that of water splitting (1.76 V). Meanwhile, S2– ions are selectively electrooxidized to sulfur with a high yield of 220.5 g h–1 m–2, realizing electrochemical upcycling of sulfur-containing pollutants. This strategy provides an attractive route for both energy-effective hydrogen generation and sulfur recycling.

Replacing oxygen evolution reaction by glycerol electrooxidation on Rh modified Ni(OH)2/C for energy-efficient hydrogen production

Oxygen evolution reaction (OER) is a key reaction for the development of green and sustainable energy system based in the production of hydrogen by electrolysis. However, the water splitting required a high overpotential for the oxygen evolution reaction. In this work we investigated the use of the Glycerol Electrooxidation Reaction (GEOR) in alkaline solutions on Rh/C, Ni(OH)2/C and Rhx{Ni(OH)2}y/C nanocomposites instead of water as a reagent in the anodic reaction in electrolyzers as a way to reduce the cell overpotential and obtain energy savings. The electrocatalysts were prepared by microwave-assisted alcohol reduction method and characterized by X-ray diffraction. The catalysts presented particles with fcc structure for Rh/C, a hexagonal structure for (Ni(OH)2/C), and (Rh0.3{Ni(OH)2}0.7/C) and (Rh0.5{Ni(OH)2}0.5/C) presented mixed structures with brucite and a α-Ni(OH)2/C structure. The electrochemical performance of Rh0.3{Ni(OH)2}0.7/C presented superior density current at low potential in comparison to the other studied materials. The potential value determined for GEOR at 10 mA cm−2 was nearly 1.29 V vs. RHE in a 0.5 mol L−1 glycerol solution that is 0.3 V less than the value obtain Rh/C in the absence on the organic species. The analysis of the products generated after bulk electrolysis using high-performance liquid chromatography demonstrated that at 1.50 V vs. RHE the main reaction products were and tartronate, glyceraldehyde and oxalate, depending on the employed catalytic material. These results demonstrated that value-added products could be obtained as a promising way to valorize by the glycerol electrooxidation besides the energy saving during the electrolysis for the hydrogen production.

Selective Adsorption Behavior Modulation on Nickel Selenide by Heteroatom Implantation and Heterointerface Construction Achieves Efficient Co-production of H2 and Formate.

Glycerol-assisted hybrid water electrolysis is a potential strategy to achieve energy-efficient hydrogen production. However, the design of an efficient catalyst for the specific reaction is still a key challenge, which suffers from the barrier of regulating the adsorption characteristics of distinctive intermediates in different reactions. Herein, a novel rationale that achieves selective adsorption behavior modulation for self-supported nickel selenide electrode by heteroatom implantation and heterointerface construction through electrodeposition is developed, which can realize nichetargeting optimization on hydrogen evolution reaction (HER) and glycerol oxidation reaction (GOR), respectively. Specifically, the prepared Mo-doped Ni3 Se2 electrode exhibits superior catalytic activity for HER, while the NiSe-Ni3 Se2 electrode exhibits high Faradaic efficiency (FE) towards formate production for GOR. A two-electrode electrolyzer exhibits superb activity that only needs an ultralow cell voltage of 1.40V to achieve 40mA cm-2 with a high FE (97%) for formate production. Theoretical calculation unravels that the introduction of molybdenumcontributes to the deviation of the d-band center of Ni3 Se2 from the Fermi level, which is conducive to hydrogen desorption. Meanwhile, the construction of the heterojunction induces the distortion of the surface structure of nickel selenide, which exposes highly active nickel sites for glycerol adsorption, thus contributing to the excellent electrocatalytic performance.