Robust cellulose fiber/fibrous sepiolite coated RuO2-CoP aerogel as monolithic catalyst for hydrogen generation via NaBH4 hydrolysis.

Commercial carriers have been used to prepare monolithic NaBH4 hydrolytic catalysts, but the fixed structure and material limit the application scope and design freedom. Herein, the RuO2-CoP catalyst is coated on the surface of fibrous sepiolite (RuO2-CoP@aSep) by in-situ deposition, annealing in air and phosphating, which is constructed into the aerogel with cellulose nanofiber (CNF) and polyvinyl alcohol (PVA) by freeze drying process. The hydrogen generation rate (HGR) of RuO2-CoP@aSep increases from 3655 to 10713mLmin-1gcatalyst-1 by adjusting the mass ratio of cobalt to ruthenium in RuO2-CoP. Moreover, the optimized composite aerogel can get HGR (5268mLmin-1gcatalyst-1) by regulating its formulation, and the catalytic activity and mass loss rate of the aerogel maintains 76.6 and 0.92 % after five cycles of testing. The synergistic interaction between Ru and Co species, micro-nano porous structure, and structural coupling provide good catalytic activity and cycling performance, and show great potential in the design of controllable NaBH4 hydrolyzed monolithic catalysts.

Oxygen vacancy-rich N-doped carbon encapsulated BiOCl-CNTs heterostructures as robust electrocatalyst synergistically promote oxygen reduction and Zn-air batteries.

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.

Engineering cobalt nitride nanosheet arrays with rich nitrogen defects as a bifunctional robust oxygen electrocatalyst in rechargeable Zn-air batteries.

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.

Interfacial Electronic Coupling of NC@WO3 -W2 C Decorated Ru Clusters as a Reversible Catalyst toward Electrocatalytic Hydrogen Oxidation and Evolution Reactions.

Designing a bifunctional catalyst for hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is significant toward developing sustainable hydrogen-electric conversion systems. Herein, a cost-effective bifunctional catalyst, Ru/N-doped Carbon@WO3 -W2 C (Ru/NC@WOC), was developed via co-precipitation and polyol reduction. Ru/NC@WOC showed superior HOR/HER activity in alkaline solution in comparison with commercial Pt/C. HOR electrochemical tests showed that the mass activity at 0.05 V (1.96  m A µ g R u - 1 ) and exchange-current density were 7.5 and 1.2 times that of Pt/C. Additionality, Ru/NC@WOC exhibited up 30-fold HOR activity in mass activity compared with benchmark Ru/C. Moreover, it also displayed exceptional electrocatalytic HER with overpotentials of 31 mV at 10 mA cm-2 and 119 mV at 100 mA cm-2 , surpassing Pt/C, benchmark Ru/C, and most of the previously reported electrocatalysts. The outstanding catalytic activity of Ru/NC@WOC probably arises from the synergy between Ru and NC@WOC matrix, suitable hydrogen binding energy, and highly conductive substrate. Thus, this work may pave a new avenue to fabricate low-cost bifunctional HOR/HER catalysts for alkaline fuel cells and water electrolyzer.

Nanowire-structured FeP-CoP arrays as highly active and stable bifunctional electrocatalyst synergistically promoting high-current overall water splitting.

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.

Structure-regulated Ru particles decorated P-vacancy-rich CoP as a highly active and durable catalyst for NaBH4 hydrolysis.

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.

Interface Engineering of Needle-Like P-Doped MoS2 /CoP Arrays as Highly Active and Durable Bifunctional Electrocatalyst for Overall Water Splitting.

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.

Metal-Organic Framework (MOF)-Derived Electron-Transfer Enhanced Homogeneous PdO-Rich Co3 O4 as a Highly Efficient Bifunctional Catalyst for Sodium Borohydride Hydrolysis and 4-Nitrophenol Reduction.

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.

Dissolution reconstruction of electron-transfer enhanced hierarchical NiSx-MoO2 nanosponges as a promising industrialized hydrogen evolution catalyst beyond Pt/C.

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.