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This study explores the use of biomass-based carbon aerogels from raspberry pulp as electrocatalysts for the hydrogen evolution reaction (HER). Producing hydrogen via alkaline water electrolysis, from renewable energy sources, is an attractive way to mitigate climate change; however, there still exists challenges in achieving high efficiency without resorting to expensive noble metal catalysts. HER electrocatalysts from transition metal-doped biomass are promising, cost efficient, durable and renewable alternative materials. Freeze dried raspberry pulp with added iron salts was pyrolyzed, resulting in carbon aerogels containing iron oxide nanoparticles. These nanoparticles were later used to grow carbon nanotubes (CNTs) by chemical vapor deposition which enhanced HER activity with overpotential reaching only 408 mV at a current density of −10 mA cm−2, an increase in performance by 30% when compared to that of aerogels without CNTs. This shows that our synthetic approach is effective for catalysis applications, and its versatility means that efficiency could be improved further by tuning the properties of iron oxide nanoparticles and the three-dimensional interconnected porous network of the carbon aerogel.

Tungsten disulfide in its metallic 1T phase is a stable and efficient electrocatalyst for the hydrogen evolution reaction. However, stabilizing the 1T phase while maintaining high conductivity and catalytic activity is challenging. Here, we addressed these issues by producing few-layered WS2 with an expanded interlayer distance of ∼10 Å, followed by the incorporation of foreign metals such as Ni, Co, or Pt. These dopants allow tuning of the 1T/2H phase ratio and limit the production of oxidized species such as WOx and SOx. In particular, the addition of only 0.3 at% of Pt leads to a preferential formation (∼70%) of the 1T-WS2 phase. Despite the ultralow Pt content, Pt-WS2 exhibited a 41% reduction in the overpotential required to reach −10 mA cm–2, a 78% decrease in charge transfer resistance, and a 14-fold increase in active surface area compared to pristine WS2. The excellent catalytic activity of Pt-WS2 is attributed to the presence of the 1T phase with a higher density of active sites, enhanced conductivity, and stronger hydrogen interaction, all facilitated by the presence of Pt. In addition, Pt-WS2 shows great performance when used as a cathode in proton exchange membrane water electrolyzers, achieving a current density of 1.75 A cm–2 at 2.1 V, 270% larger than that of pristine WS2.

Trimetallic nickel–iron–molybdenum oxides are excellent electrocatalysts for alkaline water electrolysis despite experiencing severe molybdenum dissolution. While the impact of molybdenum on fresh samples is well-understood, its substantial loss during operation without compromising performance presents a unique puzzle. Here, we show that the initial presence of molybdenum induces the formation of nickel vacancies and distorts octahedral nickel sites. This structural distortion induces charge transfer between lattice oxygen and nickel, inducing an early formation and stabilization of active nickel oxyhydroxides. Even after complete molybdenum leaching and transitioning into a bimetallic nickel-iron oxide, the catalyst retains its exceptional performance due to the persistence of distorted octahedral nickel sites. Understanding this process enables the exploration of alternative metals that could induce similar structural distortions, as well as inspire similar strategies in other electrocatalysts. (Figure presented.)

The increasing demand for green hydrogen is driving the development of efficient and durable electrocatalysts for the hydrogen evolution reaction (HER). Nickel-molybdenum (NiMo) alloys are among the best HER electrocatalysts in alkaline electrolytes, and here we report a scalable solution precursor plasma spraying (SPPS) process to produce the highly active Ni4Mo electrocatalysts directly onto metallic substrates. The NiMo coating coated onto inexpensive Ni mesh revealed an excellent HER performance with an overpotential of only 26 mV at −10 mA cm⁻² with a Tafel slope of 55 mV dec⁻¹. Excellent operational stability with minimum changes in overpotential were also observed even after extensive 60 hour high-current stability test. In addition, we investigate the influence of different substrates over the catalytic performance and operational stability. We also proposed that a slow, but consistent, dissolution of Mo is the primary degradation mechanism of NiMo-based coatings. This unique SPPS approach enables the scalable production of exceptional NiMo electrocatalysts with remarkable activity and durability, positioning them as ideal cathode materials for practical applications in alkaline water electrolysers.

Imagine a future where our cars, factories, and homes run without polluting the air. That is the idea behinda fossil-free future, a world where we no longer rely on coal, oil, or gas, but instead use clean, renewableenergy sources. One of the most promising options to make this future possible is hydrogen. Althoughhydrogen is the most abundant element in the universe, it is not available as a free resource on Earth;instead, it can be produced from water via electrolysis powered by electricity. What makes it special is itsrole as an energy carrier: it stores and delivers clean energy, and when used, it produces only water, notcarbon dioxide. This makes hydrogen the perfect companion for solar and wind power, helping us keep thelights on, power vehicles, and even run industries, all without burning fossil fuels.

Electrolyzer technology offers a direct and sustainable method for producing hydrogen from water.However, current systems depend heavily on precious metals such as Pt, Ir, and Ru, posing a significantbarrier to scalability. Addressing this challenge requires major advances in materials science to minimize theuse of scarce metals and promote the widespread use of electrolyzers. In our work, we demonstrate thatnon-precious, earth-abundant electrocatalysts can consistently deliver high efficiency and long-termstability. We developed novel synthesis routes to produce highly defective and porous nanomaterials frommetal alloys and mixed oxides to transition metal dichalcogenides. We studied their intrinsic catalyticactivity and learned to tune their performance under both alkaline and acidic conditions. This allowed us tofurther study these cost-effective electrocatalysts in anion (and proton) exchange membrane electrolyzers.Our studies show that these materials can achieve competitive efficiency and durability, providing a viablepathway to reduce reliance on noble metals and accelerate the commercialization of large-scale waterelectrolysis.

Föreställ dig en framtid där våra bilar, fabriker och hem drivs utan att förorena luften. Det är idén bakom en fossilfri framtid, en värld där vi inte längre är beroende av kol, olja eller gas, utan istället använder rena och förnybara energikällor. Ett av de mest lovande alternativen för att göra denna framtid möjlig är vätgas. Även om väte är det mest förekommande grundämnet i universum, finns det inte som en fri tillgänglig resurs på jorden; vätgas kan istället framställas ur vatten genom elektrolys som drivs av elektricitet. Det som gör vätgas särskilt intressant är dess egenskap att vara en energibärare, vätgas kan lagra och leverera ren energi, och när den används bildas endast vatten, inte koldioxid. Detta gör vätgas till det perfekta komplementet till sol och vindkraft, eftersom den kan bidra till att hålla lamporna tända, driva fordon och till och med försörja industrier, allt utan att bränna fossila bränslen.

Elektrolysteknik erbjuder en direkt och hållbar metod för att producera vätgas ur vatten. Dagens system är dock starkt beroende av ädelmetaller som platina (Pt), iridium (Ir) och rutenium (Ru), vilket innebär ett betydande hinder för storskalig tillämpning. För att övervinna denna utmaning krävs stora framsteg inom materialvetenskap, med fokus på att minimera användningen av sällsynta metaller och snabba på utveckling och installation av elektrolysteknik. I vårt arbete visar vi att icke-ädla, vanligt förekommande elektrokatalysatorer kan uppnå både hög effektivitet och långsiktig stabilitet. Vi har utvecklat nya syntesmetoder för att framställa defektrika och porösa nanomaterial från metalllegeringar och metalloxidlegeringar till blandningar av övergångsmetaller och dikalcogenider. Vi har undersökt deras katalytiska aktivitet och lärt oss att optimera deras prestanda under både alkaliska och sura reaktionsförhållanden. Detta har gjort det möjligt för oss att i nästa steg studera dessa kostnadseffektiva elektrokatalysatorer i elektrolysörer med anjon och protonutbytande membran. Våra studier visar att dessa material kan uppnå konkurrenskraftig effektivitet och hållbarhet, och därigenom påvisa en möjlig utveckling för att minska beroendet av ädelmetaller och påskynda kommersialiseringen av storskalig vattensönderdelning.

MoS₂ is widely praised as a promising replacement for Pt as an electrocatalyst for the hydrogen evolution reaction (HER), but even today, it still suffers from low performance. This issue is tackled by using Mn³⁺ as a surface modifier to trigger sulfur vacancy formation and enhance electron transport in few-layered 2H MoS₂. Only 10% of Mn is sufficient to transform the semiconductive MoS₂ into an active HER electrocatalyst. The insertion of Mn reduces both HER onset potential and Tafel slope which allows reaching 100 mA/cm² at an overpotential of 206 mV, ten times larger of what undoped MoS₂ can achieve. The enhanced activity arises because Mn³⁺ introduces electronic states near the conduction band, promotes sulfur vacancies, and increases the hydrogen adsorption. In addition to its facile production and extended shelf-life, Mn–MoS₂ exhibits an efficiency of 73% at 800 mA/cm² and 2.0 V when used in proton exchange membrane water electrolyzers.

Robust electrocatalysts required to drive the oxygen evolution reaction (OER) during water electrolysis are still a missing component toward the path for sustainable hydrogen production. Here a new family of OER active quaternary mixed-oxides based on X-Sn-Mo-Sb (X = Mn, Fe, Co, or Ni) is reported. These nonstoichiometric mixed oxides form a rutile-type crystal structure with a random atomic motif and diverse oxidation states, leading to the formation of cation vacancies and local disorder. The successful incorporation of all cations into a rutile structure was achieved using oxidizing agents that facilitates the formation of Sb⁵⁺ required to form the characteristic octahedral coordination in rutile. The mixed oxides exhibit enhanced stability in both acidic and alkaline environments under anodic potentials with no changes in their crystal structure after extensive electrochemical stress. The improved stability of these mixed oxides highlights their potential application as scaffolds to host and stabilize OER active metals.

Proton exchange membrane water electrolysis is widely used in hydrogen production, but its application is limited by significant electrocatalyst dissolution at the anode during the oxygen evolution reaction (OER). The best performing electrocatalysts to date are based on ruthenium and iridium oxides, but these experience degradation even at moderate cell potentials. Here we investigate a quaternary Sn-Sb-Mo-W mixed oxide as a protective scaffold for ruthenium oxide. The acid-stable mixed oxide consists of an interconnected network of nanostructured oxides capable of stabilizing ruthenium into the matrix (Ru-MO). In combination with titanium fibre felt, we observed a lower degradation in the oxygen evolution reaction activity compared to unprotected ruthenium oxide after the electrochemical stress test. The superior stability of Ru-MO@Ti is attributed to the presence of MO which hinders the formation of reactive higher valence ruthenium (Ru+8). Our work demonstrates the potential of multi-metal oxides to extend the lifetime of the OER active metal and the titanium support.

Foam-like NiMo coatings were produced from an inexpensive mixture of Ni, Al, and Mo powders via atmospheric plasma spraying. The coatings were deposited onto stainless-steel meshes forming a highly porous network mainly composed of nanostructured Ni and highly active Ni₄Mo. High material loading (200 mg cm⁻²) with large surface area (1769 cm² per cm²) was achieved without compromising the foam-like characteristics. The coatings exhibited excellent activity towards both hydrogen evolution (HER) and oxygen evolution (OER) reactions in alkaline media. The HER active coating required an overpotential of 42 mV to reach a current density of −50 mA cm⁻² with minimum degradation after a 24 h chronoamperometry test at −10 mA cm⁻². Theoretical simulations showed that several crystal surfaces of Ni4Mo exhibit near optimum hydrogen adsorption energies and improved water dissociation that benefit the HER activity. The OER active coating also consisting of nanostructured Ni and Ni₄Mo required only 310 mV to achieve a current density of 50 mA cm⁻². The OER activity was maintained even after 48 h of continuous operation. We envisage that the development of scalable production techniques for Ni₄Mo alloys will greatly benefit its usage in commercial alkaline water electrolysers.

Solution precursor plasma spraying is used to produce catalytic trimetallic coatings containing Ni, Fe and Mo directly onto stainless-steel mesh, Ni foam and carbon paper. The resulting material is mostly comprised of face centered cubic FeNi₃ alloy forming a highly porous coating with nanostructured features. The addition of Mo (up to ≈14 at%) generates no new crystal phases but only an increase in the lattice parameter, indicating the formation of FeNi₃Mo_x solid solutions. The FeNi₃Mo_x solid solutions are used as electrocatalyst for the hydrogen evolution reaction (HER) in alkaline media. The addition of Mo increases the HER activity significantly reaching an optimum performance at ≈9 at% Mo (FeNi₃Mo_0.40) with an overpotential at −10 mA cm⁻² of 112 mV and a Tafel slope of 109 mV dec⁻¹. The enhanced HER activity is attributed to the formation of a FeNi₃Mo_x solid solution with an increased work function that is correlated to smaller hydrogen adsorption energies. Theoretical activity maps reveal that sites near superficial Mo atoms forms catalytic hot spots and are responsible for the observed activity.