Excellent HER Research Articles

Two-dimensional AlN/TMO van der Waals heterojunction as a promising photocatalyst for water splitting driven by visible light.

In this study, the photocatalytic properties of AlN/TMO heterojunctions formed by coupling MoO2 and WO2 of transition metal oxides with AlN are studied in detail using first-principles calculations with the aim of finding efficient and low-cost photocatalysts for water splitting to produce hydrogen to reduce environmental pollution. The AIMD, phonon spectrum, and elastic constants demonstrated the thermodynamic, kinetic, and mechanical stabilities of the AlN/TMO heterojunction. The results showed that the AlN/MoO2 (1.55 eV) and AlN/WO2 (1.99 eV) heterojunctions have typical type-II energy band arrangements, which can effectively promote the separation of photogenerated electrons and hole pairs. Meanwhile, the AlN/MoO2 heterojunction showed excellent carrier mobilities (electron, 250.05 cm2 V-1 S-1 and hole, 45 467.07 cm2 V-1 S-1), which greatly exceeded those of each component. The AlN/WO2 heterojunction showed an excellent HER (-0.07 eV) performance, which was close to the expected value. For the AlN/WO2 heterojunction, a suitable band gap value, excellent HER, and other properties indicated that it has the potential to become a new candidate for photocatalytic water splitting. Our study enriches the theoretical research of transition metal oxide materials and wide-band gap materials by providing a reference direction for the design of reasonably high-quality photocatalysts.

From waste plastics to layered porous nitrogen-doped carbon materials with excellent HER performance.

Herein, layered porous nitrogen-doped carbon sheets (LPNCS) prepared from waste plastics are employed as an electrocatalytic carrier for the HER under alkaline conditions. The N-doped coral-like nanostructure with abundant meso- and macropores would shorten the proton diffusion pathway, reduce the mass transfer resistance and promote Ru dispersion. The prepared Ru/LPNCS shows an excellent performance with an overpotential of 15 mV at 10 mA cm-2, even lower than that of most reported Ru-based catalysts and the commercial Pt/C catalyst (17 mV), which provides a potential application for converting waste plastics into highly efficient HER catalysts.

Nickel-decorated RuO2 nanocrystals with rich oxygen vacancies for high-efficiency overall water splitting.

Designing transition metal-oxide-based bifunctional electrocatalysts with excellent activity and stability for OER/HER to achieve efficient water splitting is of great importance for renewable energy technologies. Herein, a highly efficient bifunctional catalysts with oxygen-rich vacancies of nickel-decorated RuO2 (NiRuO2-x) prepared by a unique one-pot glucose-blowing approach were investigated. Remarkably, the NiRuO2-x catalysts exhibited excellent HER and OER activity at 10mAcm-2 in alkaline solution with only a minimum overpotential of 51mV and 245mV, respectively. Furthermore, the NiRuO2-x overall water splitting exhibited an ultra-low voltage of 1.6V to obtain 10mAcm-2 and stability for more than 10h. XPS measurement and theoretical calculations demonstrated that the introduction of Ni-dopant and oxygen vacancies make the d-band center to lie close to the Fermi energy level, the chemical bonds between the active site and the adsorbed oxygen intermediate state are enhanced, thereby lowering the reaction activation barriers of HER and OER. The assembly of solar-driven alkaline electrolyzers facilitate the application of the NiRuO2-x bifunctional catalysts.

Anchoring Ru nanoclusters to defect-rich polymeric carbon nitride as a bifunctional electrocatalyst for highly efficient overall water splitting

The Ru nanoclusters anchored in defect-rich g-C3N4 with abundant VN were successfully prepared by one-step pyrolysis. The cooperation of defect engineering, size effect and synergistic effect endows the Ru NCs/VN-C3N4 excellent HER and OER activity.

Rapid construction of Co/CoO/CoCH nanowire core/shell arrays for highly efficient hydrogen evolution reaction.

The Co/CoO/CoCH (P-CoCH) nanowire core/shell arrays were prepared by a one step hydrothermal method and rapid reduction of cobalt carbonate hydroxide (CoCH) in Ar/H2 plasma for the first time. The rapid reduction process endows the P-CoCH with a unique porous structure, larger electrochemical active surface area and abundant activity sites. Therefore, the as-prepared P-CoCH nanowire core/shell arrays show superior HER performance with a low overpotential of 69 mV and a small Tafel slope of 47 mV dec-1 at a current density of 10 mA cm-2. In addition, the P-CoCH electrocatalyst demonstrates an excellent cycling stability without any obvious decay after 24 h continuous operation at 100 mA cm-2 current density. This study might provide a new insight into the rapidly construction of efficient HER Co-based electrocatalysts and beyond.

Hierarchical porous NiFe-P@NC as an efficient electrocatalyst for alkaline hydrogen production and seawater electrolysis at high current density

The TNiFe-P@NC presented excellent HER performance with an overpotential of 40 mV at 10 mA cm−2and excellent stability in KOH solution. An assembled NiFe-P@NC||NiFe-P@NC electrolyzer could drive 100/500 mA cm−2in alkaline seawater electrolyte at 1.77/1.93 V.

An interface engineering induced hierarchical NiCo/V2O3/C Schottky heterojunction catalyst for large-current-density hydrogen evolution reaction

A nickel foam (NF) supported NiCo/V2O3/C nanosheet heterostructure electrocatalyst benefiting from the reasonable coordination of structural engineering and interface engineering shows excellent HER activity.

RE-doped (RE = La, Ce and Er) Ni2P porous nanostructures as promising electrocatalysts for hydrogen evolution reaction.

The construction of an efficient non-noble-metal electrocatalyst towards alkaline hydrogen evolution is challenging but in great demand. The fabrication of a porous nanostructure and heteroatom doping are two productive strategies for developing effective electrocatalysts. In this contribution, we report the preparation of La, Ce and Er-doped Ni2P porous nanostructures through a facile water bath method and phosphorization strategy. The Er-doped Ni2P porous nanostructure exhibits superb hydrogen evolution reaction (HER) catalytic performance under alkaline conditions with a low cathodic overpotential of 87 mV (10 mA cm-2, glassy carbon) and a small Tafel slope of 65.4 mV dec-1. It also displays excellent electrochemical stability in alkaline electrolytes. First-principles density functional theory (DFT) calculations disclosed the mechanism of the alkaline HER catalysis. For pristine Ni2P, the P site acts as the optimal active site with the Gibbs free energy of H* absorption (ΔGH*) of 0.48 eV. After La, Ce and Er are doped, respectively, the P site is still the active center of the three doping systems. Notably, the ΔGH* value is reduced from 0.48 eV to 0.23 eV (P site in La-doped Ni2P), 0.20 eV (P site in Ce-doped Ni2P) and 0.18 eV (P site in Er-doped Ni2P), suggesting that doping with La, Ce and Er atoms plays a crucial role in decreasing the H* absorption energy on optimal P sites and the optimum active site with a smaller ΔGH* can expedite the charge transfer rate for H* midbody and H2 generation. This is particularly noticeable for Er doping, which is in accordance with the experimental result.

Si regulation of hydrogen adsorption on nanoporous PdSi hybrids towards enhancing electrochemical hydrogen evolution activity

The addition of Si can obviously change the electronic structure and hydrogen adsorption energy of Pd, thus bringing excellent HER activity to PdSi hybrids.

Post cobalt doping and defect engineering of NbSSe for efficient hydrogen evolution reaction

Post cobalt doped NbSSe was synthesized by combining chemical vapor transport and the hydrothermal method, which exhibited excellent HER performance due to the synergistic effect of cobalt doping and S/Se vacancies.

Orange-peel derived carbon-loaded low content ruthenium nanoparticles as ultra-high performance alkaline water HER electrocatalysts.

Carbon materials have a very wide range of applications in the field of electrocatalysis, both as catalyst bodies and as excellent supports for catalysts. In this work, we obtained a graphitic-like orange-peel derived carbon (OPC) material through pre-carbonization and KOH activation strategies using discarded orange-peel as a raw material. OPC has good graphitization characteristics and a few-layer structure, making it very suitable as a support for nanoparticle catalysts. In order to compare the performance of OPC, we used commercial graphene as the benchmark, made two carbon materials uniformly loaded with ruthenium nanoparticles under the same conditions, and obtained two HER catalysts (Ru/OPC and Ru/rGO). The results indicate that Ru/OPC has excellent HER catalytic performance under alkaline conditions, not only superior to Ru/rGO, but also surpassing commercial Pt/C. In 1 M KOH; the overpotential of Ru/OPC is only 3 mV at -10 mA cm-2, greatly exceeding those of Ru/rGO (100 mV) and Pt/C (31 mV). Under high current density (j), the performance of Ru/OPC is even better; the overpotential is 79 mV and 136 mV at -100 mA cm-2 and -200 mA cm-2, respectively. More importantly, Ru/OPC also has a very high TOF and long-term stability, with a TOF of up to 10.62 H2 s-1 at an overpotential of 100 mV and almost no attenuation after 72 h of operation at -50 mA cm-2. Ru/OPC also exhibits good catalytic performance under acidic conditions, significantly superior to that of Ru/rGO. For Ru/OPC, the overpotential is 86 mV, 167 mV and 214 mV at -10 mA cm-2, -100 mA cm-2 and -200 mA cm-2, respectively. Under the same conditions, the overpotential of Ru/rGO is 143 mV, 253 mV and 306 mV at -10 mA cm-2, -100 mA cm-2 and -200 mA cm-2, respectively.

A 1,3,5-triazine and benzodithiophene based donor-acceptor type semiconducting conjugated polymer for photocatalytic overall water splitting

Donor–acceptor domains hold the key to tailoring photochemical properties and charge carrier mobility of conjugated microporous polymers (CMPs) for application in photocatalytic water splitting. Herein, a family of electron-withdrawing 1,3,5-triazine and electron-donating fused thiophene based porous polymers are obtained via C–H arylation. The TBT-BDT showed an excellent HER of 4238 ​μmol ​g−1 ​h−1, which is 17-fold and 3-fold higher than that of TBT-Th and TBT-TT, respectively. In addition, TBT-BDT facilitates overall water splitting to produce stoichiometric amounts of H2 (28 ​μmol ​g−1 ​h−1) and O2 (14 ​μmol ​g−1 ​h−1). The significant difference in the photocatalytic performance was mainly ascribed to the band structure change of the polymers, which underlined the importance of the donor unit on the performance of D−A type photocatalysts and indicated that thiophene-contained unit BDT is an excellent donor for high photocatalytic activity.

Solid phase synthesis Ni3N and N-CNT synergetic corn-like multifunctional electrocatalyst

Nickel nitride (Ni3N) based catalysts have been studied extensively as oxygen evolution and hydrogen evolution reaction (OER/HER) catalysts because of good stability in alkaline solution. However, relatively poor electrical conductivity of Ni3N seriously restricted electron transfer from the Ni3N nanoparticles surfaces to inner substrates for highly efficient water splitting. In this work, solid phase synthesis strategy is implemented to prepare Ni3N/N-CNT composite. Ni3N/N-CNT shows impressive onset potential (0.81 V) and half wave (0.70 V) in oxygen reduction reaction (ORR), respectively. The higher limiting diffusion current of Ni3N/N-CNT shows the faster ORR kinetics. Ni3N was anchored on N-CNT, which displayed an outstanding OER and HER performance. The low OER overpotential (0.40 V) indicated that the Ni3N nanoparticles on N-CNT has significant enhancement of the OER activity. Significantly, Ni3N/N-CNT displays an excellent HER activity with preferable current density and low overpotential of 259 mV at 10 mA cm−2. The excellent multifunctional catalytic property is due to the electronic interaction between Ni3N and N-CNT which is beneficial for the mass and electron transfer. The conclusion broadens our understanding for exploit multifunctional catalysts.

Ag‐doped CoP Hollow Nanoboxes as Efficient Water Splitting Electrocatalysts and Antibacterial Materials

AbstractFunctionalized designs such as doping can effectively reduce charge transfer impedance and accelerate charge transfer dynamics. In this study, we reported a facile method to synthesize Ag‐doped ZIF‐67 hollow nanoboxes (Ag‐CoP HNBs) by introducing Ag into cobalt‐centered zeolitic imidazolate framework (ZIF‐67). Its unique hollow structure results in higher stability, more active sites and bigger specific surface area with excellent HER and OER performance. Specifically, Ag‐CoP HNBs requires only 97 and 256 mV to achieve a current density of 10 mA cm−2 for HER and OER in 1.0 M KOH, respectively. Meanwhile, merely a voltage of 1.53 V is needed for delivering a current density of 10 mA cm−2 for overall water splitting. Moreover, Ag‐CoP HNBs exhibits excellent antibacterial activity for different bacteria due to the presence of Ag. In conclusion, this study provided a facile, feasible and productive way for developing Ag contained bifunctional electrocatalysts with antibacterial activity, which might have potential use in seawater splitting.

Ruthenium doped commercial carbon cloth for efficient electrocatalytic hydrogen evolution reaction

The heterogenous electrochemical catalyst of activated carbon cloth coupled with Ru doping was fabricated via a facile hydrothermal method. The obtained activated carbon cloth coupled with Ru catalyst possesses outstanding hydrogen evolution reaction performance even superior than 40 % Pt/C catalyst in alkaline system. • Commercial carbon cloth was activated via facile hydrothermal process for the first time. • The Ru atoms anchored on carbon cloth act as the new active centers. • Ru/CC exhibited excellent HER activity and strong stability in alkaline solution. • Low overpotential of 24 mV and Tafel slope of 51.5 mV dec −1 was delivered at 10 mA cm −2 . Ru atoms are doped on the surface of commercial carbon cloth (Ru/CC) through a simple and facile hydrothermal process and the catalytic inert surface of CC is activated. The activated Ru/CC exhibit excellent HER electrocatalytic activity in 1 M KOH solution. The Ru/CC-0.1 catalyst has a small overpotential of 24 mV at 10 mA cm −2 and low Tafel slope of 51.5 mV dec −1 .

Combined nano/micro-structure of Ni12P5-Ni2P nanorod array for effective wide pH range HER and overall alkaline water-splitting

• A self-supported Ni 12 P 5 -Ni 2 P-NR@NF was fabricated. • The Ni 12 P 5 -Ni 2 P-NR@NF demonstrated excellent HER (ŋ 10 was 107 mV, 138 mV and 168 mV in acidic, neutral and alkaline electrolyte, respectively) and overall water-splitting activity (ŋ 20 = 1.53 V, with stability of ∼120 h) in alkaline media. • The combination of unique structure and intrinsic chemical properties was responsible for the excellent electrocatalysis performance of Ni 12 P 5 -Ni 2 P-NR@NF. A self-supported Ni phosphide nanorod array (Ni 12 P 5 -Ni 2 P-NR@NF) was synthesized using a one-step method to produce a multifunctional electrocatalyst. Benefiting from the unique structure and intrinsic chemical properties, the Ni 12 P 5 -Ni 2 P-NR@NF demonstrated excellent HER activity across a range of pH values and overall water-splitting in alkaline media. To achieve a current density of 10 mA cm −2 , the optimized Ni 12 P 5 -Ni 2 P-NR@NF required an overpotential of 107 mV, 138 mV and 168 mV in acidic, neutral and alkaline electrolyte, respectively. In addition, when used as both anode and cathode for a two-electrode electrolyze to perform water electrolysis in 1.0 M KOH, the cell only needed 1.53 V to achieve 20 mA cm −2 with stability of ∼120 h, providing evidence of multifunctional potential for large-scale applications.

Enhanced electrocatalytic water splitting by Sm and Gd-doped ceria electrocatalysts on Ni foam substrate

CeO2 is attractive for water splitting due to its various valence oxidation states, however, its catalytic performance in alkaline medium is challenging. In this study, we synthesized novel ceria-based electrocatalysts: Gd-doped CeO2 nanocrystals (GDC) and Sm-doped CeO2 nanospheres (SDC) on Ni foam using sol–gel and one-step hydrothermal methods, respectively. These ceria-based electrocatalysts, GDC and SDC, depict excellent activity in the OER and HER, respectively. The GDC/NF showed promising OER performance, achieving an exceptional overpotentials of 300 and 420 mV to keep current densities of 10 and 100 mA cm−2, respectively. In addition, SDC/NF exhibited excellent HER activity with overpotentials of 117 and 325 mV to reach current densities of 10 and 100 mA cm-2, respectively. Furthermore, both GDC and SDC were ultra-stable at a fixed current density of 50 mA cm−2 for 25 h. Moreover, the complete anion-exchange membrane (GDC/NF||SDC/NF) demonstrated 1.6 Vcell to accomplish 10 mA cm-2 current density, with ultra-durability for 40 h at 50 mA cm-2. The versatile electrochemical performance of ceria-based catalysts is attributed to diverse-valence Ce3+/Ce4+ redox states and positive entropy contribution of the f0–f1 transition. Notably, doping with Gd and Sm led to an easy and strong reduction owing to the oxygen voids created and hydroxyls. Moreover, dopants stabilized ceria and assisted the generation of metal–H groups, which improved the kinetic activity of ceria for electrochemical water splitting.

CuAl layered double hydroxide as a highly efficient electrocatalyst for the electrolysis of water into hydrogen and oxygen fuels

The production of green H2 through water electrolysis processes has become a prominent technology to deal with energy and environmental crisis worldwide. The total energy consumption of electrolysis processes can be reduced by the development of low-cost electrocatalysts. In this paper, we report first time the synthesis of a highly efficient 2D CuAl LDH electrocatalyst to produce the green H2. The electrocatalyst was characterized with the help of various analytical instruments such as FT-IR, XRD, BET, TGA, ICP-OES, and XPS. The morphological characterization was done by SEM and TEM. The electrochemical characterization such as CV, LSV, Tafel plot, and EIS was done in acidic, basic, seawater, and alkaline seawater medium. It was found that CuAl LDH electrocatalyst exhibits a good current density of 100 mA/cm2 at a potential of 1.178 V in acidic medium and 10 mA/cm2 at 1.114V in seawater medium. It was investigated that the CuAl LDH behaves as a bifunctional electrocatalyst and exhibits excellent HER and OER activity in an acidic medium. The effect of temperature on the efficiency of the electrocatalyst under the above electrolyte mediums was also studied. The electrochemical data suggests that the CuAl LDH electrocatalyst can be utilized in an alkaline/PEM electrolyzer to produce the green H2 at an industrial scale with optimum cost.

Bifunctional electrocatalysts of CoFeP/rGO heterostructure for water splitting

Bifunctional non-precious electrocatalysts with high performance are highly desired for renewable energy but remain challenging. Herein, a CoFeP/rGO heterostructure was rational developed based on the synergistic effect, including superior conductivity, increased catalytic active sites of rGO support and the regulated electron distribution of bimetallic phosphide. At a current of 10 mA cm−2, the CoFeP/rGO-2 composite exhibits excellent HER activity with low overpotentials of 101 mV and 76 mV in 1.0 M KOH and 0.5 M H2SO4 electrolyte, respectively. And highly active alkaline OER performance was provided with an overpotential of only 275 mV to reach a current density of 10 mA cm−2. By the way, the CoFeP/rGO-2 electrode showed a pleasured working voltage of 1.58 V for overall water splitting in alkaline environment. More importantly, the long term durability and higher stability of the catalysts demonstrated their feasibility of bimetallic phosphide/rGO system as bifunctional electrocatalysts.

Electrospun porous carbon nanofibers decorated with iron-doped cobalt phosphide nanoparticles for hydrogen evolution

Developing highly active and cost-effective electrocatalysts to replace noble metal catalysts is the main route for the efficient production of green hydrogen. Herein, we have successfully fabricated iron-doped cobalt phosphide nanoparticles-decorated porous carbon nanofibers (Fe-CoP/PCNF) by a facile three-step method. On one hand, the electrospun nanofibers could serve as porous and conductive substrate for the exposure of active sites and the fast charge transfer; On the other hand, the Fe-CoP nanoparticles with optimized hydrogen adsorption free energy showed high intrinsic catalytic activity. Hence, the Fe-CoP/PCNF achieves excellent HER performance, which affords overpotential of 151 mV to support the current density of 10 mA cm −2 in acid media. Moreover, the nanoparticles were protected by a carbon layer, preventing the electrocatalyst from corrosion during long-term operation. The findings may shed light on the rational exploration of nanofibrous electrocatalysts for highly efficient hydrogen evolution. • Fe-doped CoP nanoparticles are conveniently generated on electrospun porous carbon nanofiber. • The Fe-doped CoP nanoparticles possess high intrinsic catalytic activity for HER. • Porous carbon nanofibers with massive active sites and high conductivity are beneficial to the HER performance.