Antiperovskite Nitrides as Efficient and Durable Electrocatalysts for Industrially Relevant Hydrogen Evolution

Exploring materials with high hydrogen evolution reaction (HER) performance is of importance for the development of clean hydrogen energy, and the defects on the surfaces of catalysts are essential. In this work, we evaluate the HER performance among group IVA monochalcogenides MXs (M = Ge/Sn, X = S/Se) with M/X point defects on the edges. Compared with basal planes and bare edges, the GeS edge with Ge vacancy (ΔGH* = 0.016 eV), GeSe edge with Se vacancy (ΔGH* = 0.073 eV), and SnSe edge with Sn vacancy (ΔGH* = -0.037 eV) hold the best HER performances, which are comparable to or even better than the value for Pt (-0.07 eV). Furthermore, the relationships between ΔGH* and p-band centers of considered models are summarized. The stability of proposed electrocatalysts are analyzed by vacancy-formation energy and strain engineering. In summary, the HER performance of MXs is greatly improved by introduction of point defects at the edges, which is promising for their use as electrocatalysts for the conversion and storage of energy in the future.

Metal/antiperovskite metal nitride composites Ag/AgNNi3 as novel efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Searching for cost-efficient electrocatalysts with high catalytic activity and stability for hydrogen generation by means of water electrolysis would make a great improvement on energy technologies field. Herein, we report high-performance hydrogen evolution reaction (HER) electrocatalysts based on sulfur-doped Ni5P4 nanoplate arrays grown on carbon paper (S-Ni5P4 NPA/CP). This ternary, robust, monolithic S-Ni5P4 NPA/CP exhibits remarkable performance for the HER compared to nickel phosphide and nickel sulfide catalysts. The S-Ni5P4 NPA/CP with ∼6% S presents the most promising behavior for water electrolysis applications. Specifically, it shows an onset potential of 6 mV, needing overpotentials (η) of 56 and 104 mV to attain current densities of 10 and 100 mA cm-2 with a Tafel slope of 43.6 mV dec-1. The turnover frequency of 6% S-Ni5P4 NPA/CP is about 0.11 s-1 at overpotential of 100 mV, which is ca. 10 and 40 times that of Ni5P4 NPA/CP and NiS2 NPA/CP, respectively. It also shows remarkable stability and durability in 0.5 M H2SO4 solution. The results indicate that S and P tune the electronic properties mutually and produce an active catalyst phase for the HER. Furthermore, the density functional theory calculations show that S-Ni5P4 NPA/CP exhibits only 0.04 eV of hydrogen adsorption free energy(Δ GH*), which is more suitable than Pt (∼-0.09 eV). We propose that the S-doping not only restrains the surface oxidation and dissolution of S-Ni5P4 NPA/CP in acid solution but also reduces the Δ GH*. We believe that our work will provide a new strategy to design transition metal phosphide composite materials for practical applications in catalysis and energy fields.

Dilute molybdenum atoms embedded in hierarchical nanoporous copper accelerate the hydrogen evolution reaction

The intrinsic electronic and structural properties of the transition metal rhenium (Re) endow it with substantial application potential in electrocatalysis. However, the high cost of Re requires the development of Re-based materials to reduce cost and optimize the performance at the same time. Herein, a one-step high-pressure and high-temperature (HPHT) synthetic strategy is proposed for fabricating Re-C phase gradient composites, presenting a facile and efficient pathway to develop high-performance hydrogen evolution reaction (HER) electrocatalysts. By studying the structural evolution of Re toward ReC and uncovering its intrinsic mechanism, the regulation of the material’s electrocatalytic activity was successfully realized. Experimental results confirm that HPHT conditions of 5 GPa and 1400 °C effectively induce the formation of multiple crystalline phases of Re-C solid solution and ReC in the Re-C composite. These phases have coherent phase boundaries and form the phase gradient composites. Compared with element Re, the synergistic effect of phase gradient composites broadens the electronic state range by increasing electron transfer from Re to C in ReC (increasing the binding energy) and reduces the binding energy in Re-C solid solution. The broad electronic states range in the phase gradient composites exhibits optimal HER overpotentials of 150 mV (acidic electrolyte) and 166 mV (alkaline electrolyte) at 10 mA cm−2. These findings provide a promising strategy to boost catalysts’ electrocatalytic performance via constructing phase gradient composites.

Controllable fabrication of abundant nickel-nitrogen doped CNT electrocatalyst for robust hydrogen evolution reaction

Hydrogen evolution reaction (HER) plays a vital role in renewable energy conversion for the development of hydrogen-based energy sources. Lately, heterostructures through hybridizing MXenes with two-dimensional materials have been successfully fabricated and attract much attention due to the exceptional performance as electrodes for Li ion storage and electrocatalysts for HER. Herein, we constructed heterostructures of CoNx-graphene (CoNx-G, x = 2 and 4) supported by MXenes (Ti3C2F2 and Ti3C2O2) monolayer as highly active electrocatalysts for HER. The theoretical results show that the CoN2-G/Ti3C2O2 heterostructure exhibits a high performance for HER with an over-potential (Ƞ) of only 0.33 V, and the rate-limiting step is determined to be the initial water dissociation process in alkaline media. The outstanding performance of CoN2-G/Ti3C2O2 is strongly attributed to the interfacial coupling between CoN2-G and the MXene substrate. Our finding demonstrates that the sluggish hydrogen evolution process in alkaline media can be facilitated by taking advantage of the fast charge transfer kinetics and interfacial coupling of MXenes. Herein, we theoretically design and explore 2D hybrid materials of CoNx–G supported by MXene monolayers as highly active HER electrocatalysts by using first-principles calculations. The results show that the CoN2–G/Ti3C2O2 heterostructure has an outstanding HER performance with ΔGH* (0.21 eV) approaching zero as well as water molecule dissociation barrier (ΔGH–OH) of 0.30 eV in alkaline media. This exceptional performance is strongly attributed to the interfacial coupling between CoN2–G and the MXene substrate.

High-performance hydrogen evolution reaction (HER) catalysts are compelling for the conversion of renewable electricity to fuels and feedstocks. The best HER catalysts rely on the use of platinum and show the highest performance in acidic media. Efficient HER catalysts based on inexpensive and Earth-abundant elements that operate in neutral (hence biocompatible) media could enable low-cost direct seawater splitting and the realization of bio-upgraded chemical fuels. In the challenging neutral-pH environment, water splitting is a multistep reaction. Here we present a HER catalyst comprising Ni and CrOx sites doped onto a Cu surface that operates efficiently in neutral media. The Ni and CrOx sites have strong binding energies for hydrogen and hydroxyl groups, respectively, which accelerates water dissociation, whereas the Cu has a weak hydrogen binding energy, promoting hydride coupling. The resulting catalyst exhibits a 48 mV overpotential at a current density of 10 mA cm−2 in a pH 7 buffer electrolyte. These findings suggest design principles for inexpensive, efficient and biocompatible catalytic systems. Integrating electrocatalytic H2 production with biological H2-fed systems for CO2 upgrading requires H2 generation to occur in biocompatible media—typically with neutral pH. Here, the authors design multi-site H2 evolution catalysts that minimize the water dissociation barrier and promote hydride coupling in neutral media.

Encapsulating dual-phased Mo2C-WC nanocrystals into ultrathin carbon nanosheet assemblies for efficient electrocatalytic hydrogen evolution

Molybdenum disulfide (MoS2 ) is one of the most promising alternatives to the Pt-based electrocatalysts for the hydrogen evolution reaction (HER). However, its performance is currently limited by insufficient active edge sites and poor electron transport. Hence, enormous efforts have been devoted to constructing more active edge sites and improving conductivity to obtain enhanced electrocatalytic performance. Herein, the 3D carbon foam (denoted as CF) supported edge-rich N-doped MoS2 nanoflakes were successfully fabricated by using the commercially available polyurethane foam (PU) as the 3D substrate and PMo12 O40 3- clusters (denoted as PMo12 ) as the Mo source through redox polymerization, followed by sulfurization. Owing to the uniform distribution of nanoscale Mo sources and 3D carbon foam substrate, the as-prepared MoS2 -CF composite possessed well-exposed active edge sites and enhanced electrical conductivity. Systematic investigation demonstrated that the MoS2 -CF composite showed high HER performance with a low overpotential of 92 mV in 1.0 m KOH and 155 mV in 0.5 m H2 SO4 at a current density of 10 mA cm-2 . This work offers a new pathway for the rational design of MoS2 -based HER electrocatalysts.

The effective electrocatalysts for hydrogen evolution reaction (HER) in alkaline aqueous is critical point to reduce energy losses for water electrolysis. Here, a highly active and stable electrochemical catalyst of platinum (Pt) nanoparticles loaded on three-dimensional Ti3C2Tx-reduced graphite oxide (rGO) hybrid support (Pt/Ti3C2Tx-rGO3D) has been developed for hydrogen evolution reaction (HER). The large surface of 3 D support provides an adequate site for deposition of Pt nanoparticles, leading to superior HER activity with low overpotential about 41 mV and better stability than Pt/C. This study offers a hybrid support for the development of highly active electrocatalysts for hydrogen evolution reaction.

Core-shell Ni2P@CoP nanoarrays supported on NF as a highly efficient electrocatalyst for hydrogen evolution reaction

Perpendicularly anchored ReSe2 nanoflakes on reduced graphene oxide support for highly efficient hydrogen evolution reactions

Green application of trimetallic nickel-cobalt-molybdenum nanocomposites on 3D graphene oxide as a powerful electrocatalyst for hydrogen evolution reaction

The rational structural and compositional design of Pt-based electrocatalysts is effective in synergizing the physicochemical and electrochemical properties of Pt for developing high-performance hydrogen evolution reaction (HER) electrocatalysts.