Active and stable electrocatalysts made from earth-abundant elements are key to water splitting for hydrogen production through electrolysis. The growth of NiSe nanowire film on nickel foam (NiSe/NF) in situ by hydrothermal treatment of NF using NaHSe as Se source is presented. When used as a 3D oxygen evolution electrode, the NiSe/NF exhibits high activity with an overpotential of 270 mV required to achieve 20 mA cm(-2) and strong durability in 1.0 M KOH, and the NiOOH species formed at the NiSe surface serves as the actual catalytic site. The system is also highly efficient for catalyzing the hydrogen evolution reaction in basic media. This bifunctional electrode enables a high-performance alkaline water electrolyzer with 10 mA cm(-2) at a cell voltage of 1.63 V.

An Fe-doped CoP nanoarray behaves as a robust 3D monolithic multifunctional catalyst for electrolytic and hydrolytic hydrogen evolution with high activity. Its two-electrode electrolyzer needs a cell voltage of only 1.60 V for 10 mA cm water-splitting current. It also catalyzes effectively NaBH hydrolysis with a low activation energy of ≈39.6 kJ mol and a hydrogen generation rate of 6.06 L min g .

Replacement of precious Pt with earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) holds great promise for clean energy devices, but the development of low-cost and durable HER catalysts with Pt-like activity is still a huge challenge. In this communication, we report on the development of self-standing ternary FeCoP nanowire array on carbon cloth (FeCoP/CC) as a Pt-free HER catalyst with activities being strongly related to Fe substitution ratio. Electrochemical tests show that FeCoP/CC not only possesses Pt-like activity with the need of overpotential of only 37 mV to drive 10 mA cm, outperforming all non-noble-metal HER catalysts reported to date, but demonstrates superior long-term durability in 0.5 M HSO. Density functional theory calculations further reveal that Fe substitution of Co in CoP leads to more optimal free energy of hydrogen adsorption to the catalyst surface. This study offers us a promising flexible monolithic catalyst for practical applications.

It is highly attractive but challenging to develop earth-abundant electrocatalysts for energy-saving electrolytic hydrogen generation. Herein, we report that Ni P nanoarrays grown in situ on nickel foam (Ni P/NF) behave as a durable high-performance non-noble-metal electrocatalyst for hydrazine oxidation reaction (HzOR) in alkaline media. The replacement of the sluggish anodic oxygen evolution reaction with such the more thermodynamically favorable HzOR enables energy-saving electrochemical hydrogen production with the use of Ni P/NF as a bifunctional catalyst for anodic HzOR and cathodic hydrogen evolution reaction. When operated at room temperature, this two-electrode electrolytic system drives 500 mA cm at a cell voltage as low as 1.0 V with strong long-term electrochemical durability and 100 % Faradaic efficiency for hydrogen evolution in 1.0 m KOH aqueous solution with 0.5 m hydrazine.

In this communication, we report a two-step strategy for low-temperature construction of Ni2P nanoparticle films supported on a Ti plate (Ni2P/Ti). When used as an integrated hydrogen evolution cathode, the Ni2P/Ti electrode exhibits remarkable catalytic activity, superior stability and nearly 100% Faradaic efficiency in acidic solutions, and it needs overpotentials of 138 and 188 mV to afford current densities of 20 and 100 mA cm(-2), respectively.

Oriented external electric fields (OEEFs) offer a unique chance to tune catalytic selectivity by orienting the alignment of the electric field along the axis of the activated bond for a specific chemical reaction; however, they remain a key experimental challenge. Here, we experimentally and theoretically investigated the OEEF-induced selective catalysis in a two-step cascade reaction of the Diels-Alder addition followed by an aromatization process. Characterized by the mechanically controllable break junction (MCBJ) technique in the nanogap and confirmed by nuclear magnetic resonance (NMR) in bottles, OEEFs are found to selectively catalyze the aromatization reaction by one order of magnitude owing to the alignment of the electric field on the reaction axis. Meanwhile, the Diels-Alder reaction remained unchanged since its reaction axis is orthogonal to the electric fields. This orientation-selective catalytic effect of OEEFs reveals that chemical reactions can be selectively manipulated through the elegant alignment between the electric fields and the reaction axis.

Active and stable electrocatalysts made from earthabundant elements are key to water splitting for hydrogen production through electrolysis.The growth of NiSe nanowire film on nickel foam (NiSe/NF) in situ by hydrothermal treatment of NF using NaHSe as Se source is presented. When used as a3 Do xygen evolution electrode,t he NiSe/NF exhibits high activity with an overpotential of 270 mV required to achieve 20 mA cm À2 and strong durability in 1.0 m KOH, and the NiOOH species formed at the NiSe surface serves as the actual catalytic site.T he system is also highly efficient for catalyzing the hydrogen evolution reaction in basic media. This bifunctional electrode enables ah igh-performance alkaline water electrolyzer with 10 mA cm À2 at ac ell voltage of 1.63 V.Hydrogen has been considered as ac lean energy resource to replace the diminishing fossil fuel. [1,2] Electrochemical water splitting is awell-established commercial technology to convert electricity produced from intermittent renewable energy resources (such as solar energy,w ind, wave power) into chemical energy stored by hydrogen fuel, addressing the issues of effective storage and transport.[3] Although offering an effective way to make high-purity hydrogen, its practical use for mass hydrogen production is limited because it is as trongly uphill reaction with large overpotential (commercial electrolyzers typically operating at ac ell voltage of 1.8-2.0 V, which is much higher than the theoretical minimum value of 1.23 V).[4] Active electrocatalysts for anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER) are implemented to overcome the large water-splitting overpotentials,m aking the process more energy-efficient.[5] Currently,I r-and Ru-based compounds have the highest activity toward the OER, [6] and platinum group metals are the most efficient HER catalysts, [7] but they suffer from scarcity and high cost, limiting their widespread use.I ti st hus attractive to design efficient OER and HER catalysts made from earth-abundant elements and, indeed, great progress has been achieved during the past years in developing non-precious metal catalysts with high activity for OER (cobalt phosphate, [8] oxides, [9][10][11][12] hydroxides [13][14][15][16][17] )a nd HER (chalcogenides, [18][19][20][21] carbides, [22,23] phosphides [7,[24][25][26][27] ). Water splitting must be performed in either strongly acidic or alkaline solution to minimize the overpotentials, [28] which however is challenging for earth-abundant catalysts because ahigh-efficiencycatalyst at acidic pH may be inactive or even unstable at alkaline pH and vice versa. Using ab ifunctional OER and HER catalyst has advantages of simplifying the system and lowering the cost. Because acidic water splitting suffers from the use of scarce and expensive acid-insoluble OER catalysts with reasonable activity, [29] alkaline water splitting has emerged as as trong candidate for commercialization toward mass hydrogen production.[4] It is thus highly attractive to make...

The development of efficient bifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of extreme importance for future renewable energy systems. This Communication reports the recent finding that room-temperature treatment of CoO nanowire array on Ti mesh by NaBH in alkaline media leads to in situ development of CoB nanoparticles on nanowire surface. The resulting self-supported CoB@CoO nanoarray behaves as a 3D bifunctional electrocatalyst with high activity and durability for both HER (<17% current density degradation after 20 h electrolysis) and OER (<14% current density degradation after 20 h electrolysis) with the need of the overpotentials of 102 and 290 mV to drive 50 mA cm in 1.0 m KOH, respectively. Moreover, its two-electrode alkaline water electrolyzer also shows remarkably high durability and only demands a cell voltage of 1.67 V to deliver 50 mA cm water-splitting current with a current density retention of 81% after 20 h electrolysis. This work provides a promising methodology for the designing and fabricating of metal-boride based nanoarray as a high-active water-splitting catalyst electrode for applications.