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The development of non-precious metal catalysts for oxygen reduction reactions (ORR) is vital for promising clean energy technologies such as fuel cells, and zinc-air batteries. Herein, we present a stepwise synthesis of N-doped and carbon encapsulated BiOCl-CNTs heterostructures. Electrocatalytic ORR studies show that the optimized catalyst has a high half-wave potential (E1/2) of 0.85 V (vs. RHE), large limiting current density (-5.34 mA cm−2@0.6 V) in alkaline medium, and nearly perfect 4e− reduction characteristics, even surpassing commercial Pt/C. Meanwhile, the catalyst has exceptional durability (above 97.5 % after 40000 s) and strong resistance towards methanol poisoning. The good ORR activity also results in high-performance zinc-air batteries with a specific capacity (724 mAh g−1@10 mA cm−2), a high open-circuit potential of 1.51 V and a peak power density of 170.7 mW cm−2, as well as an ultra-long charge–discharge cycle stability (155 h), comparable with the Pt/C catalyst. The catalytic mechanism reveals that the excellent electrocatalytic performance originates from the synergistic effect of N doping, oxygen vacancies, and BiOCl sites.

Developing high-activity bifunctional oxygen electrocatalysts to overcome the sluggish 4e− kinetics is an urgent challenge for rechargeable metal-air batteries. Here, we prepared a CoN nanosheet catalyst with rich nitrogen defects (CoN-Nd) through solvothermal and low-temperature nitridation. Notably, the study finds for the first time that only Co LDH materials can be mostly converted to CoN-Nd under the same nitriding conditions relative to different Co-based precursors. Experiments indicate that the constructed CoN-Nd catalyst exhibits preeminent electrocatalytic activities for both oxygen evolution reaction (η10 = 243 mV) and oxygen reduction reaction (JL = 5.2 mA cm−2). Moreover, the CoN-Nd-based Zinc-air battery showed a large power density of 120 mW cm−2 and robust stability over 260 cycles, superior to the state-of-art Pt/C + RuO2. The superior performance is attributed to a large number of defects formed by the disordered arrangement of local atoms on the catalyst that facilitate the formation of more active sites, and alternate array-like structures thereof improving electrolyte diffusion and gas emission.

The design and construction of highly efficient and durable non-noble metal bifunctional catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media is essential for developing the hydrogen economy. To achieve this goal, we have developed a bifunctional nanowire-structured FeP-CoP array catalyst on carbon cloth with uniform distribution through in-situ hydrothermal growth and phosphating treatment. The unique nanowire array structure and the strong electronic interaction between FeP and CoP species have been confirmed. Electrochemical studies have found that the designed Fe0.14Co0.86-P/CC catalyst appears excellent HER (130 mV@10 mA cm−2)/OER (270 mV@10 mA cm−2) activity and stability. Moreover, the bifunctional Fe0.14Co0.86-P/CC(+/−) catalyst is also used in simulated industrial water splitting system, where the pair catalyst requires about 1.95 and 2.14 V to reach 500 and 1000 mA cm−2, even superior to the control RuO2(+)||Pt/C(−) catalyst, showing good industrial application prospects. These excellent electrocatalytic properties are attributed to the synergy between FeP and CoP species as well as the unique microstructure, which can accelerate charge transfer, expose more active sites and enhance electrolyte diffusion and gas emissions.

NaBH4 is considered the best hydrogen storage material due to its high hydrogen content of 10.6 wt% and good stability. However, NaBH4 hydrolysis requires an efficient catalyst because of the sluggish reaction kinetics. In this work, we have demonstrated a process of preparing a cobalt phosphide-supported Ru particulate nanocatalyst with abundant phosphorus vacancies for the first time. Electron paramagnetic resonance and transmission electron microscopy revealed that the synthesized Ru9.8/r-CoP catalyst has ample phosphorus vacancies, and Ru species are small particles (~2.5 nm) with uniform dispersion, respectively. More importantly, the optimized Ru9.8/r-CoP catalyst has the lowest activation energy (45.3 kJ mol−1) and exhibits excellent catalytic performance for NaBH4 hydrolysis with a high hydrogen generation rate 9783.3 mLH2 min−1 gcat−1 at 25 °C, which is higher than most of the cobalt-based catalysts. Moreover, the Ru9.8/r-CoP catalyst also shows good reusability. For example, the catalytic performance only declined by ca. 14% after five cycles. The excellent catalytic performance of Ru9.8/r-CoP is attributed to the abundant phosphorus vacancies along with a large specific surface area of r-CoP, which makes the Ru particles smaller and more uniformly dispersed on the surface, thereby exposing more active sites to show improved performance.

Developing a bifunctional water splitting catalyst with high efficiency and low cost are crucial in the electrolysis water industry. Here, we report a rational design and simple preparation method of MoS2 -based bifunctional electrocatalyst on carbon cloth (CC). The optimized P-doped MoS2 @CoP/CC catalyst presents low overpotentials for the hydrogen (HER) and oxygen evolution reactions (OER) of 64 and 282 mV in alkaline solution as well as 72 mV HER overpotential in H2 SO4 at a current density of 10 mA cm-2 . Furthermore, P-MoS2 @CoP/CC as a bifunctional catalyst delivered relatively low cell voltages of 1.83 and 1.97 V at high current densities of 500 and mA cm-2 in 30 % KOH. The two-electrode system showed a remarkable stability for 30 h, even outperformed the benchmark RuO2 ||Pt/C catalyst. The excellent electrochemical performance can be credited to the unique microstructure, high surface area, and the synergy between metal species. This study presents a possible alternative for noble metal-based catalysts to overcome the challenges of industrial applications.

Developing a bifunctional catalyst with low cost and high catalytic performance in NaBH4 hydrolysis for H2 generation and selective reduction of nitroaromatics will make a significant impact in the field of sustainable energy and water purification. Herein, a low-loading homogeneously dispersed Pd oxide-rich Co3 O4 polyhedral catalyst (PdO-Co3 O4 ) with concave structure is reported by using a metal-organic framework (MOF)-templated synthesis method. The results show that the PdO-Co3 O4 catalyst has an exceptional turnover frequency (3325.6 molH2 min-1 molPd-1 ), low activation energy (43.2 kJ mol-1 ), and reasonable reusability in catalytic H2 generation from NaBH4 hydrolysis. Moreover, the optimized catalyst also shows excellent catalytic performance in the NaBH4 selective reduction of 4-nitrophenol to 4-aminiphenol with a high first-order reaction rate of approximately 1.31 min-1 . These excellent catalytic properties are mainly ascribed to the porous concave structure, monodispersed Pd oxide, as well as the unique synergy between PdO and Co3 O4 species, which result in a large specific surface area, high conductivity, and fast solute transport and gas emissions.

The rational design of non-precious-metal bifunctional catalysts of oxygen and hydrogen evolution reactions that generate a high current density and stability at low over potentials is of great significance in the field of water electrolysis. Herein, we report a facile and controllable method for the in-situ growth of urchin-like FeOOH–NiOOH catalyst on Ni foam (FeOOH–NiOOH/NF). X-ray photoelectron spectroscopy confirms that the proportion of Ni and Fe species with high valence state gradually increase with the extension of growth time. Electrochemical studies have shown that the optimized FeOOH–NiOOH/NF-24 h and −12 h catalysts demonstrate excellent electrochemical activity and stability in oxygen/hydrogen evolution reactions. Moreover, the cell voltage is reduced around 0.15 V at high current density (0.5–1.0 A cm−2) as compared to the state-of the art RuO2/NF(+)||Pt–C/NF(−) system, far better than most of the previously reported catalysts. The cost analyst revealed that using FeOOH–NiOOH/NF catalyst as both electrodes could potentially reduce the price of H2 around 7% compared with traditional industrial electrolyzers. These excellent electrocatalytic properties can be attributed to the unique urchin-like structure and the synergy between Ni and Fe species, which can not only provide more active sites and accelerate electron transfer, but also promote electrolyte transport and gas emission.

Construction of oxygen evolution electrocatalysts with abundant oxygen defects and large specific surface areas can significantly improve the conversion efficiency of overall water splitting. Herein, we adopt a controlled method to prepare oxygen defect-rich double-layer hierarchical porous Co3O4 arrays on nickel foam (DL-Co3O4/NF) for water splitting. The unique array-like structure, crystallinity, porosity, and chemical states have been carefully investigated through SEM, TEM, XRD, BET, and XPS techniques. The designated DL-Co3O4/NF has oxygen defects of up to 67.7% and a large BET surface area (57.4 m2 g−1). Electrochemical studies show that the catalyst only requires an overpotential of 256 mV to reach 20 mA cm−2, as well as a small Tafel slope of 60.8 mV dec−1, which is far better than all control catalysts. Besides, the catalyst also demonstrates excellent overall water splitting performance in a two-electrode system and good long-term stability, far superior to most previously reported catalysts. Electrocatalytic mechanisms indicate that abundant oxygen vacancies provide more active sites and good conductivity. At the same time, the unique porous arrays facilitate electrolyte transport and gas emissions, thereby synergistically improving OER catalytic performance.

An industrial electro-catalyst obliges three essential features, such as scalability, generating high current density at low overpotential, and long-term stability. Herein, we tackle those challenges using NiSx-MoO2 nanosponges on carbon cloth based hydrogen evolution catalyst. The target catalyst was synthesized through a series of simple and scalable methods, including dissolution, reconstruction, and chemical vapor deposition. The optimized NiSx-MoO2/CC catalyst exhibits a superior hydrogen evolution catalytic activity far better than commercial Pt/C meanwhile surpasses widely used industrial Raney Ni catalyst by many aspects, namely lower overpotential at 500 mA cm−2 current density and smaller Tafel plot in 30 wt% KOH solution. This excellent electrocatalytic activity is attributed to enhanced mass transfer and faster reaction kinetics due to the unique hierarchical porous structures, as well as the synergistic electron transfer effect between the two components of NiSx and MoO2 species. This work may provide a new strategy for the design of better hydrogen evolution catalyst for industrial application.

Hydrogen is one of the most promising energy carriers to replace fossil fuels and electrolyzing water to produce hydrogen is a very effective method. However, designing highly active and stable non-precious metal hydrogen evolution electrocatalysts that can be used in universal pH is a huge challenge. Here, we have reported a simple strategy to develop a highly active and durable non-precious MoO2-Ni electrocatalyst for hydrogen evolution reaction (HER) in a wide pH range. The MoO2-Ni catalyst exhibits a superior electrocatalytic performance with low overpotentials of 46, 69, and 84 mV to reach −10 mA cm−2 in 1.0 M KOH, 0.5 M H2SO4 , and 1.0 M PBS electrolytes, respectively. At the same time, the catalyst also shows outstanding stability over a wide pH range. It is particularly noted that the catalytic performance of MoO2-Ni in alkaline solution is comparable to the highest performing catalysts reported. The outstanding HER performance is mainly attributed to the collective effect of the rational morphological design, electronic structure engineering, and strong interfacial coupling between MoO2 and Ni in heterojunctions. This work provides a viable method for the synthesis of inexpensive and efficient HER electrocatalysts for the use in wide pH ranges.

The continuous on-site production of H2O2 using an inexpensive metal catalyst based electrochemical approach as the alternative of the widely used complex anthraquinone process is particularly promising. Although tremendous progress has been made in recent years towards developing oxygen reduction reaction (ORR) catalyst for H2O2 production, fabricating highly active, selective, and stable H2O2 catalyst that works at high pH is always the challenge. Here, we describe a rationally designed non-precious metal-based nitrogen-doped Fe2O3-carbon nanotubes (NC@Fe2O3-CNTs) catalyst, which not only exhibits high ORR activity and low overpotential but also shows a unique selectivity towards H2O2 generation (97.3%) in alkaline media. Moreover, the NC@Fe2O3-CNTs catalyst retains a much higher relative current after continuous operation for 10 h, as compared to commercial Pt/C catalyst. The optimized NC@Fe2O3-CNTs shows the superior overall performance of H2O2 generation as compared to the present catalysts under high pH. The catalytic mechanism analysis indicates that the nitrogen species, Fe chemical states, oxygen vacancies and CNTs skeleton play important roles in improving the selectivity and current density of H2O2 generation.

The fabrication of highly active oxygen reduction reaction (ORR) catalysts with strong anti-poisoning and durability at low cost is extremely desirable but still remains a great challenge. Herein, a novel hierarchically structured material of N-doped porous carbon spheres embedded with monodispersed Fe2O3 clusters (Fe2O3/NPCS) is constructed. The composition and microstructure of Fe2O3/NPCS are carefully characterized, and the existed Fe2O3-stabilized Fe N4 active sites for ORR are verified. The Fe2O3/NPCS catalyst exhibits a superior ORR activity with a positive half-wave potential of 0.95 V, showing an obvious around 90 mV positive-shift over commercial Pt/C (20 wt%). Additionally, the high ORR catalytic activity is also accompanied by a smaller Tafel slope of 45.3 mV decade−1 than Pt/C, implying a fast kinetics at high potentials. Furthermore, the high-active catalyst also demonstrates an outstanding anti-poisoning capacity and long-term durability. The excellent ORR activites are attributed to the synergistic effect between the rich Fe N4 active sites protected by Fe2O3 clusters, the porous structures facilitating electron transport as well as the electrolyte and oxygen diffusion.

Developing a bifunctional water splitting catalyst with high efficiency and low cost are crucial in the electrolysis water industry. Here, we report a rational design and simple preparation method of MoS

NaBH

Developing a bifunctional catalyst with low cost and high catalytic performance in NaBH

Designing a highly active and stable catalyst for NaBH4 hydrolysis is a key step towards overcoming the challenges of hydrogen storage. Herein, we have developed a controllable strategy to fabricate a series of hierarchically structured cobalt-ruthenium-phosphide arrays on nickel foam (Co–Ru–P@NF) as a highly efficient and stable catalyst for hydrogen generation from NaBH4 hydrolysis in alkaline media. SEM and TEM analyses show that the interconnected rugae-like Co–Ru–P arrays are vertically grown on the surface of Ni foam, together with uniformly distributed RuP3 nanoclusters on the surface of CoP nanosheets. More importantly, the optimized Co–Ru–P@NF catalyst exhibits an outstanding catalytic performance on NaBH4 hydrolysis in alkaline media with a high turnover frequency (TOF) of 2123.6 molH2 min−1 molRu−1 at 25 °C, which is one of the highest known so far. Furthermore, the exceptional catalytic performance is in line with the outcome of low activation energy (40.3 kJ mol−1). Additionally, the catalyst also shows a high stability with less than 8.0% lost after 5 consecutive cycles. The superior catalytic performance is ascribed to the synergetic effect between RuP3 and CoP species resulting in a significant electron transfer effect, together with the unique morphologies associated with a large specific surface area and open-channels for effective solute transport/adsorption and H2 gas emissions.

The electrocatalytic oxygen evolution reaction (OER) is the bottleneck to overall water splitting because of the slow kinetics of the four-electron transfer process. Therefore, it is of great significance to develop OER electrocatalysts with high activity, long durability, and scalability. Herein, we present a selenium-coated cobalt selenide (CoSe2@Se) catalyst that was first synthesized by in-situ growth on carbon cloth (CC) surface by hydrothermal method, followed by soaking treatment to prepare a three-dimensional coral-like Fe2O3-CoSe2@Se/CC composite. Electrochemical studies revealed that the optimized Fe2O3-CoSe2@Se/CC catalyst only requires 250 mV to reach 10 mA cm−2 current density, yields a small Tafel slope (50.2 mV dec−1), and has good stability (10 mA cm−2@70 h) in the electrocatalytic OER process. The overall water splitting using Fe2O3-CoSe2@Se/CC as anode only requires 1.58 and 1.69 V to achieve 10 and 100 mA cm−2, respectively, much better than most previously reported catalysts. Analysis showed that the three-dimensional coral-like morphology exposing more active sites and the synergy between different species (giving rise to, inter alia, a favorable electronic structure that lowers the electrode overpotential) are the key to the observed improved electrocatalytic performance. This work provides a novel strategy for the rational design of nanostructured OER hybrid catalysts in the future.

Developing high-efficient non-noble metal-based catalysts for oxygen reduction reaction (ORR) is an inevitable way to improve Zinc-air batteries' performance (ZAB). Herein, we report a Cu3P/MoP electrocatalyst (Cu3P/MoP@C) supported by hollow-porous-carbon nanospheres displaying high electrocatalytic activity and exceptional durability in alkaline media. The optimized ORR catalyst outperformed the benchmark Pt/C (20 wt%) and most recently reported Cu-/Mo-based catalysts in various aspects. X-ray photoelectron spectroscopy reveals that the excellent ORR performance originates from the charge transfer between of Cu3P and MoP species. Besides, the large specific surface area of Cu3P/MoP@C with mesoporous structure is particularly advantageous for the inner surface contact with electrolyte to accelerate ORR kinetics. Moreover, Cu3P/MoP@C also exhibits a large power density of 156 mW cm−2, a high round-trip efficiency, and superb stability over 231 h superior to Pt/C in the ZAB. This work offers a scalable and promising approach for the rational fabrication of hollow porous structure materials.

An industrial electro-catalyst obliges three essential features, such as scalability, generating high current density at low overpotential, and long-term stability. Herein, we tackle those challenges using NiS

Deeply understanding the structure and electrical properties of ZIF-8 is very important due to many practical applications of porous materials. We present the crystal structure and microstructure details of ZIF-8 prepared in three different solvents. The solvents play an important role on grain growth of ZIF-8, furthermore, a small fraction of monoclinic phase can be found in the ZIF-8s prepared in water or in amonium hydroxide. Radio-frequency dielectric and impedance spectra studies of dynamic dielectric response of ZIF-8s indicate two additional dielectric relaxation processes associated with the introduced water molecules in as-prepared samples. The dielectric response can be described by the combination of the dc conductivity, the universal dielectric response, the Cole-Cole relation and intrinsic response. The results exhibit the solvents make an important influence on the electrical properties due to different contents water in ZIF-8s. Our results will pave a way to modify the dielectric property of ZIF-based dielectrics in radio-frequency applications.

The electrical behavior of hybrid ZIF-8/conducting composites remains poorly understood. Here, the hybrid ZIF-8/CNT composites are synthesized by an in situ growth of ZIF-8 on carbon nanotubes (CNT). The crystal structure, morphology and dielectric properties of the composites were investigated. Dielectric permittivity of as-prepared composites is improved more than 10 times by introduced CNT. The composites have a low percolation threshold (3.2%), where the dc conductivity increases by 4–5 orders of magnitude near the percolation threshold. Furthermore, we find three dielectric relaxation processes in the as-prepared ZIF-8 and ZIF-8/1%CNT composite by electrical modulus. One low-frequency dielectric relaxation associates with Maxwell-Wagner effect between composites and electrodes, while the two high-frequency dielectric relaxation attributes to the short-range hopping process of carries or dipoles orientation. The work provides deep insights on the intrinsic and extrinsic dielectric responses of ZIF-8 based composites and on the percolation behavior of hybrid ZIF-8/conducting materials composites.

Designing a bifunctional catalyst that performs hydrolysis of metal hydrides and water reduction spontaneously is an essential step towards developing an integrated H2 storage system. Herein, a series of rugae-like CoP-Ni2P arrays decorated Ni foam (Ni-Cox-P@NF) are fabricated by two-step electrodeposition followed by phosphating treatment. The optimized Ni-Co20-P@NF catalyst shows a superior catalytic H2 generation by NaBH4 hydrolysis, giving a specific H2 generation rate of 4323.0 mL min−1 g−1 catalyst and good reusability, far better than most previously reported catalysts. Besides, the catalyst also exhibits an excellent electrocatalytic hydrogen evolution reaction with a low overpotential of 67.0 mV to reach −10 mA cm−2, small Tafel slope and long-term stability in 1.0 M KOH. The outstanding catalytic H2 generation capacity is attributed to the synergistically catalytic effect between the Ni2P and CoP species, as well as the unique composite structure with the benefit of solute transport and gas emission.