Efficient catalytic water splitting demands advanced catalysts to improve the slow kinetics of the oxygen evolution reaction (OER). Earth-abundant transition metal oxides show promising OER activity in alkaline media. However, most experimental information available is either from post-mortem studies or in situ space-averaged X-ray techniques in the micrometer range. Therefore, the composition of the active centers under operando conditions is still under debate. In this work, we combine nanoscopic and spectroscopic measurements on the hydroxylation of molecular beam epitaxy (MBE)-prepared Ni and NiFe oxides nanoislands with operando local investigations of Ni and NiFe hydroxide electrocatalysts under OER conditions to reveal the nature of the active centers in 2D OER catalysts. Our results reveal that Fe doping increases the active surface area by island fragmentation, and boosts the intrinsic activity by creating optimized active centers consisting of both Ni and Fe atoms. In addition, our findings show that operando characterization at the nanoscale is crucial to reveal the dynamic nature of the interface of 2D catalysts under reaction conditions.

Research on electrical energy conversion, storage and generation dates back to the nineteenth century, but only in recent years have scientists begun to investigate the impact of electron spin on these processes. The ability to control and manipulate this intrinsically quantum property of matter opens new approaches to addressing energy science challenges. The chiral-induced spin selectivity (CISS) effect is central to this effort, as it enables control over the transport and generation of both pure spin currents and spin-polarized charge currents. In this Review, we first introduce design strategies for implementing CISS in materials and then describe examples of how CISS has been used to improve electrocatalysis and spintronics. We conclude with a forward-looking perspective on the next steps for leveraging CISS in energy science. The chiral-induced spin selectivity (CISS) effect offers a unique approach to control and manipulate electron spin properties. In this Review, we summarize how the CISS effect is being leveraged to improve efficiency in energy science technologies.

A central challenge in water electrolysis lies with the oxygen evolution reaction (OER) where the formation of molecular oxygen (O 2 ) is hindered by the constraint of angular momentum conservation. While the reactants OH − or H 2 O are diamagnetic (DM), the O 2 product has a paramagnetic (PM) triplet ground state, requiring a change in spin configuration when being formed. This constraint has prompted interest in spin‐selective catalysts as a means to facilitate OER. In this context, the roles of magnetism and chirality‐induced spin selectivity (CISS) in promoting the OER reaction have recently been investigated through both theoretical and experimental studies. However, pinpointing the key principles and their relative contribution in mediating spin‐enhancement remains a significant challenge. This roadmap offers a forward‐looking perspective on current experimental trends and theoretical developments in spin‐enhanced OER electrocatalysis and outlines strategic directions for integrating incisive experiments and operando approaches with computational modeling to disentangle key mechanisms. By providing a conceptual framework and identifying critical knowledge gaps, this perspective aims to guide researchers toward dedicated experimental and computational studies that will deepen the understanding of spin‐induced OER enhancement and accelerate the development of next‐generation catalysts.

Oxygen evolution (OER) and oxygen reduction (ORR) reactions are central to the efficiency of electrolysis and fuel cells, involving the paramagnetic triplet ground state of oxygen and the singlet ground state of water. Here, we demonstrate that spin-polarized currents enhance the ORR activity. Using a silver-coated nickel electrode over a neodymium (Nd) magnet, we observed that ORR performance is maximized when the Ag layer is thinner than the spin diffusion length of silver─conditions under which spin alignment at the electrode-electrolyte interface is maintained. In contrast, experiments with thicker Ag layers lead to spin relaxation and diminished electrocatalytic activity. A model description of this system shows that a substantial spin polarization at the interface is accompanied by a large two-electron transfer, which satisfies conservation of angular momentum during ORR. These findings highlight the critical role of spin-selective charge transfer and offer insights into the control of reaction pathways in oxygen electrocatalysis.

Electrolytic hydrogen is identified as a crucial component in the desired decarbonisation of the chemical industry, utilizing renewable energy to split water into hydrogen and oxygen. Water electrolysis still requires important scientific advances to improve its performance and lower its costs. One of the bottlenecks in this direction is related to the sluggish anodic oxygen evolution reaction (OER). Producing anodes with competitive performance remains challenging due to the high energy losses and the harsh working conditions typically required by this complex oxidation process. Recent advancements point to spin polarization as an opportunity to enhance the kinetics of this spin-restricted reaction, yielding the paramagnetic O2 molecule. One powerful strategy deals with the generation of chiral catalytic surfaces, typically by surface functionalisation with chiral organic molecules, to promote the chiral-induced spin selectivity (CISS) effect during electron transfer. However, the relationship between optical activity and enhanced electrocatalysis has been established only from indirect experimental evidence. In this work, we have exploited operando electrochemical and spectroscopic tools to confirm the direct relationship between the faster OER kinetics and the optical activity of enantiopure Fe-Ni metal oxides when compared with that of achiral catalysts in alkaline conditions. Our results show the participation of chiral species as reactive intermediates during the electrocatalytic reaction, supporting the appearance of a mechanistic CISS enhancement. Furthermore, these intrinsically chiral transition-metal oxides maintain their enhanced activity in full cell electrolyser architectures at industrially relevant current densities.

Magnetic-field enhancement of the oxygen evolution reaction (OER) represents a promising route toward more efficient alkaline water electrolyzers, yet its origin remains debated due to overlapping effects of mass transport and reaction kinetics. Here, we present a general experimental strategy that employs strong forced convection to suppress uncontrolled transport arising from natural diffusion and magnetohydrodynamic (MHD) flows. Using polycrystalline Au electrodes, we show that this approach resolves subtle OER variations under controlled flow and field conditions. Notably, spontaneous MHD flows near hard-magnetic electrodes are identified for the first time, highlighting a major complication in interpreting magnetic effects. Forced convection eliminates these artifacts, enabling reliable quantification of intrinsic activity changes. Systematic analysis of 3d transition-metal catalysts reveals a clear composition dependence: Fe-based catalysts exhibit the strongest magnetic enhancement, followed by Mn and Co, whereas Ni shows minimal response. Moreover, synergistic interactions between different elements further modulate the effect. By decoupling magnetic influences on mass transport from those on kinetics, this method provides a universal framework to assess how magnetic fields alter electrocatalysis.

The reversible formation of hydrogen bonds is a ubiquitous mechanism for controlling molecular assembly in biological systems. However, achieving predictable reversibility in artificial two-dimensional (2D) materials remains a significant challenge. Here, we use an external electric field (EEF) at the solid/liquid interface to trigger the switching of H-bond-linked 2D networks using a scanning tunneling microscope. Assisted by density functional theory and molecular dynamics simulations, we systematically vary the molecule-to-molecule interactions, i.e., the hydrogen-bonding strength, as well as the molecule-to-substrate interactions to analyze the EEF switching effect. By tuning the building block's hydrogen-bonding ability (carboxylic acids vs aldehydes) and substrate nature and charge (graphite, graphene/Cu, graphene/SiO2), we induce or freeze the switching properties and control the final polymorphic output in the 2D network. Our results indicate that the switching ability is not inherent to any particular building block but instead relies on a synergistic combination of the relative adsorbate/adsorbate and absorbate/substrate energetic contributions under surface polarization. Furthermore, we describe the dynamics of the switching mechanism based on the rotation of carboxylic groups and proton exchange, which generate the polarizable species that are influenced by the EEF. This work provides insights into the design and control of reversible molecular assembly in 2D materials, with potential applications in a wide range of fields, including sensors and electronics.

The direct enhancement of electrocatalytic oxygen evolution reaction (OER) by a magnetic field is a novel strategy for high-efficiency alkaline water electrolysers. The influence of a magnetic field on either electrochemical equilibria or electron-transfer kinetics remains controversial, partially due to the difficulty of eliminating the mass-transfer related effects. In this work, a magneto-electrochemical system, which contains a thin-layer flow cell allowing a forced convection flow, is designed to decouple the magnetic effects on mass transfer from those on the reaction kinetics. When OER is catalyzed by magnetic materials, the active species on the surface, rather than the composition and magnetic property of the bulk material, determine the magneto-enhancement of the reaction kinetics. The enhancement at monometallic active sites follow the order Ni3+ < Co3+ < Fe3+, corresponding to the change in kinetic overpotential (ΔEk) of 2.7, 18.8, and 42.9 mV at 1 mA·cm-2, respectively. It was assumed that a magnetic field acts on the spin moments of active sites, leading to variations in the d-band center and the electrochemical equilibria. Here we show that the magneto-enhancement follows the same trend of the average spin moments in the order Ni < Co < Fe. Thus, the spin state of active sites determines the ΔEk on magnetic electrocatalysts.

Magnetic field effects on electrocatalysis have recently gained attention due to the substantial enhancement of the oxygen evolution reaction (OER) on ferromagnetic catalysts. When detecting an enhanced catalytic activity, the effect of magnetic fields on mass transport must be assessed. In this study, we employ a specifically designed magneto-electrochemical system and non-magnetic electrodes to quantify magnetic field effects. Our findings reveal a marginal enhancement in reactions with high reactant availability, such as the OER, whereas substantial boosts exceeding 50% are observed in diffusion limited reactions, exemplified by the oxygen reduction reaction (ORR). Direct visualization and quantification of the whirling motion of ions under a magnetic field underscore the importance of Lorentz forces acting on the electrolyte ions, and demonstrate that bubbles' movement is a secondary phenomenon. Our results advance the fundamental understanding of magnetic fields in electrocatalysis and unveil new prospects for developing more efficient and sustainable energy conversion technologies. Magnetic fields can enhance electrocatalysis, yet its effect on mass transport has been overlooked. Here, the authors track the motion induced on the electrolyte ions, demonstrating that mass transport effects can double the catalyst activity with low reactant availability, as in oxygen reduction.

In the last decade, photo-assisted water splitting to generate hydrogen and oxygen has become a key process in the quest for clean energy technologies. In this context, the sluggish kinetics of the oxygen evolution reaction (OER) is still a limitation. The combination of an efficient electrocatalyst with a light-absorbing species can provide an output boost by the additional input of solar energy. In this work, we used ordered mesoporous nanocrystalline TiO2 thin films as a photoactive phase that contain embedded NiFe-based double-layered hydroxides (NiFe-LDH) catalysts for the OER in the mesopores. The structural and electrochemical properties of these materials were studied, taking into account the effect of the Ni:Fe ratio and concentration. Our results indicate that this material shows synergy in the photo-assisted water-splitting activity, as the total current is higher than the combined contributions of dark NiFeOx electrocatalysis and TiO2 photocurrent. Optimization of the NiFe ratio (9:1) and deposition time (60 s) produced an enhancement of up to 18 % in the total current at 1.50 V.

Controlling product selectivity is essential for improving the efficiency of multi-product reactions. Electrochemical water oxidation is a reaction of main importance in different applications, e.g., renewable energy schemes and environmental protection, where H2O2 and O-2 are the two principal products. In this Communication, the product selectivity of electrochemical water oxidation was controlled by making use of the chiral induced spin selectivity (CISS) effect at mesoporous-TiO2 on the molecule-modified Au substrate. Our results show a decrease in H2O2 formation when using chiral hetero-helicene molecules adsorbed on the Au substrate. We propose a mechanism for this kinetic effect based on the onset of CISS-induced spin polarization on the Au-helicene chiral interface. We also present a new tunable substrate to investigate the CISS mechanism.

Efficient catalytic water splitting demands advanced catalysts to improve the slow kinetics of the oxygen evolution reaction (OER). Earth-abundant transition metal oxides show promising OER activity in alkaline media. However, most experimental information available is either from post-mortem studies or in-situ space-averaged X-ray techniques in the micrometer range. Therefore, the composition of the active centers under operando conditions is still under debate. In this work, we combine nanoscopic and spectroscopic measurements on the hydroxylation of molecular beam epitaxy (MBE)-prepared Ni and NiFe oxides nanoislands with operando local investigations of Ni and NiFe hydroxide electrocatalysts under OER conditions to reveal the nature of active centers of Ni and Fe-doped Ni oxides in 2D OER catalysts. Our results reveal that Fe doping increases the active surface area by island fragmentation and boosts the intrinsic activity by creating optimized active centers consisting of both Ni and Fe atoms. In addition, our findings show that operando characterization at the nanoscale is crucial to reveal the dynamic nature of the interface of 2D catalysts under reaction conditions.

A sustainable future demands a successful transition from a carbon-energy dependent economy towards renewable energy schemes, many of which ultimately rely on the development of efficient electrocatalysis that either converts chemical energy into electricity or uses electrons to produce chemical energy. In general, electrocatalysis studies focus on the interactions (e.g., electron transfer) between the catalyst surface and the reaction intermediates. However, the role of electron spin, as an intrinsic property of electrons, has commonly been overlooked. Recently, controlling the electron spin polarization at the catalyst’s surface demonstrated the great potential of boosting both reaction activity and product selectivity. Molecule-induced electron spin polarization inspired by the chiral-induced spin selectivity (CISS) effect has started to have a remarkable impact in electrocatalysis. In this compact review, we summarize the latest studies that use molecule-induced electron spin polarization to enhance catalytic performance. We focus on the reactions essential to the so-called hydrogen economy, and discuss the feasibility and limitations of this effect. Finally, we share our perspective regarding the more impactful future applications.