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Carbonate formation is the primary source of energy and carbon losses in low-temperature carbon dioxide electrolysis. Realigning research priorities to address the carbonate problem is essential if this technology is to become a viable option for renewable chemical and fuel production. Low-temperature carbon dioxide electrolysis is an attractive process for sustainable fuel synthesis, but current systems suffer from low efficiency. In this comment, authors discuss the limitations arising from the reaction between carbon dioxide and hydroxide, highlighting the need for new research to address this fundamental problem.

Precisely modulating the Ru-O covalency in RuO x for enhanced stability in proton exchange membrane water electrolysis is highly desired. However, transition metals with d -valence electrons, which were doped into or alloyed with RuO x , are inherently susceptible to the influence of coordination environment, making it challenging to modulate the Ru-O covalency in a precise and continuous manner. Here, we first deduce that the introduction of lanthanide with gradually changing electronic configurations can continuously modulate the Ru-O covalency owing to the shielding effect of 5 s /5 p orbitals. Theoretical calculations confirm that the durability of Ln-RuO x following a volcanic trend as a function of Ru-O covalency. Among various Ln-RuO x , Er-RuO x is identified as the optimal catalyst and possesses a stability 35.5 times higher than that of RuO 2 . Particularly, the Er-RuO x -based device requires only 1.837 V to reach 3 A cm −2 and shows a long-term stability at 500 mA cm −2 for 100 h with a degradation rate of mere 37 μV h −1 . Lack of stability in RuO 2 -based catalysts at industrial currents impedes their use in green hydrogen production. Here, the authors show that incorporating lanthanide elements into RuO x shields against external factors, enabling fine-tuned Ru-O covalency for durable oxygen evolution reaction electrocatalysis.

The poor stability of Ru-based acidic oxygen evolution (OER) electrocatalysts has greatly hampered their application in polymer electrolyte membrane electrolyzers (PEMWEs). Traditional understanding of performance degradation centered on influence of bias fails in describing the stability trend, calling for deep dive into the essential origin of inactivation. Here we uncover the decisive role of reaction route (including catalytic mechanism and intermediates binding strength) on operational stability of Ru-based catalysts. Using MRuO x (M = Ce 4+ , Sn 4+ , Ru 4+ , Cr 4+ ) solid solution as structure model, we find the reaction route, thereby stability, can be customized by controlling the Ru charge. The screened SnRuO x thus exhibits orders of magnitude lifespan extension. A scalable PEMWE single cell using SnRuO x anode conveys an ever-smallest degradation rate of 53 μV h −1 during a 1300 h operation at 1 A cm −2 . The poor stability of ruthenium-based catalysts has greatly hampered their application in polymer electrolyte membrane water electrolysis. Here, the authors uncover the decisive role of reaction route on catalytic performance, which enables the screening of efficient ruthenium-based water oxidation catalysts.

Electrocatalytic urea synthesis emerged as the promising alternative of Haber–Bosch process and industrial urea synthetic protocol. Here, we report that a diatomic catalyst with bonded Fe–Ni pairs can significantly improve the efficiency of electrochemical urea synthesis. Compared with isolated diatomic and single-atom catalysts, the bonded Fe–Ni pairs act as the efficient sites for coordinated adsorption and activation of multiple reactants, enhancing the crucial C–N coupling thermodynamically and kinetically. The performance for urea synthesis up to an order of magnitude higher than those of single-atom and isolated diatomic electrocatalysts, a high urea yield rate of 20.2 mmol h −1 g −1 with corresponding Faradaic efficiency of 17.8% has been successfully achieved. A total Faradaic efficiency of about 100% for the formation of value-added urea, CO, and NH 3 was realized. This work presents an insight into synergistic catalysis towards sustainable urea synthesis via identifying and tailoring the atomic site configurations. The direct electrocatalytic synthesis of urea via C–N coupling is of great significance. The authors report a diatomic catalyst with bonded Fe–Ni pairs to improve the efficiency of electrochemical urea synthesis from nitrate and CO 2 .

Ruthenium dioxide is presently the most active catalyst for the oxygen evolution reaction (OER) in acidic media but suffers from severe Ru dissolution resulting from the high covalency of Ru-O bonds triggering lattice oxygen oxidation. Here, we report an interstitial silicon-doping strategy to stabilize the highly active Ru sites of RuO 2 while suppressing lattice oxygen oxidation. The representative Si-RuO 2 −0.1 catalyst exhibits high activity and stability in acid with a negligible degradation rate of ~52 μV h −1 in an 800 h test and an overpotential of 226 mV at 10 mA cm −2 . Differential electrochemical mass spectrometry (DEMS) results demonstrate that the lattice oxygen oxidation pathway of the Si-RuO 2 −0.1 was suppressed by ∼95% compared to that of commercial RuO 2 , which is highly responsible for the extraordinary stability. This work supplied a unique mentality to guide future developments on Ru-based oxide catalysts’ stability in an acidic environment. RuO 2 is highly active toward the acidic electrochemical oxygen evolution reaction but exhibits instability due to lattice oxygen oxidation. Here, authors prepare an interstitial Si-decorated RuO 2 catalyst with improved stability for acidic water oxidation by suppressing lattice oxygen oxidation.

Platinum (Pt) has found wide use as an electrocatalyst for sustainable energy conversion systems 1 – 3 . The activity of Pt is controlled by its electronic structure (typically, the d -band centre), which depends sensitively on lattice strain 4 , 5 . This dependence can be exploited for catalyst design 4 , 6 – 8 , and the use of core–shell structures and elastic substrates has resulted in strain-engineered Pt catalysts with drastically improved electrocatalytic performances 7 , 9 – 13 . However, it is challenging to map in detail the strain–activity correlations in Pt-catalysed conversions, which can involve a number of distinct processes, and to identify the optimal strain modification for specific reactions. Here we show that when ultrathin Pt shells are deposited on palladium-based nanocubes, expansion and shrinkage of the nanocubes through phosphorization and dephosphorization induces strain in the Pt(100) lattice that can be adjusted from −5.1 per cent to 5.9 per cent. We use this strain control to tune the electrocatalytic activity of the Pt shells over a wide range, finding that the strain–activity correlation for the methanol oxidation reaction and hydrogen evolution reaction follows an M-shaped curve and a volcano-shaped curve, respectively. We anticipate that our approach can be used to screen out lattice strain that will optimize the performance of Pt catalysts—and potentially other metal catalysts—for a wide range of reactions. By depositing platinum shells on palladium-based nanocubes, the strain can be controlled by through phosphorization and dephosphorization, making it possible to tune the electrocatalytic activity of the platinum shells.

Hydrogen spillover phenomenon of metal-supported electrocatalysts can significantly impact their activity in hydrogen evolution reaction (HER). However, design of active electrocatalysts faces grand challenges due to the insufficient understandings on how to overcome this thermodynamically and kinetically adverse process. Here we theoretically profile that the interfacial charge accumulation induces by the large work function difference between metal and support (∆ Φ ) and sequentially strong interfacial proton adsorption construct a high energy barrier for hydrogen transfer. Theoretical simulations and control experiments rationalize that small ∆ Φ induces interfacial charge dilution and relocation, thereby weakening interfacial proton adsorption and enabling efficient hydrogen spillover for HER. Experimentally, a series of Pt alloys-CoP catalysts with tailorable ∆ Φ show a strong ∆ Φ -dependent HER activity, in which PtIr/CoP with the smallest ∆ Φ  = 0.02 eV delivers the best HER performance. These findings have conclusively identified ∆ Φ as the criterion in guiding the design of hydrogen spillover-based binary HER electrocatalysts. Despite the significance of hydrogen spillover on metal-supported electrocatalysts for hydrogen evolution, fundamental understandings on such a process are insufficient. Here the authors show that small work function difference between metal and support facilitates hydrogen spillover and enhances activity.

Electrochemical CO 2 reduction (CO 2 R) to ethylene and ethanol enables the long-term storage of renewable electricity in valuable multi-carbon (C 2+ ) chemicals. However, carbon–carbon (C–C) coupling, the rate-determining step in CO 2 R to C 2+ conversion, has low efficiency and poor stability, especially in acid conditions. Here we find that, through alloying strategies, neighbouring binary sites enable asymmetric CO binding energies to promote CO 2 -to-C 2+ electroreduction beyond the scaling-relation-determined activity limits on single-metal surfaces. We fabricate experimentally a series of Zn incorporated Cu catalysts that show increased asymmetric CO* binding and surface CO* coverage for fast C–C coupling and the consequent hydrogenation under electrochemical reduction conditions. Further optimization of the reaction environment at nanointerfaces suppresses hydrogen evolution and improves CO 2 utilization under acidic conditions. We achieve, as a result, a high 31 ± 2% single-pass CO 2 -to-C 2+ yield in a mild-acid pH 4 electrolyte with >80% single-pass CO 2 utilization efficiency. In a single CO 2 R flow cell electrolyzer, we realize a combined performance of 91 ± 2% C 2+ Faradaic efficiency with notable 73 ± 2% ethylene Faradaic efficiency, 31 ± 2% full-cell C 2+ energy efficiency, and 24 ± 1% single-pass CO 2 conversion at a commercially relevant current density of 150 mA cm −2 over 150 h. CO 2 electroreduction to multi-carbon products in acids remains challenging due to the low efficiency and poor stability of C–C coupling. Here, the authors show that asymmetric CO binding at confined nanointerfaces enhances multi-carbon production, improves CO 2 utilization, and limits H 2 evolution.

While inheriting the exceptional merits of single atom catalysts, diatomic site catalysts (DASCs) utilize two adjacent atomic metal species for their complementary functionalities and synergistic actions. Herein, a DASC consisting of nickel-iron hetero-diatomic pairs anchored on nitrogen-doped graphene is synthesized. It exhibits extraordinary electrocatalytic activities and stability for both CO 2 reduction reaction (CO 2 RR) and oxygen evolution reaction (OER). Furthermore, the rechargeable Zn-CO 2 battery equipped with such bifunctional catalyst shows high Faradaic efficiency and outstanding rechargeability. The in-depth experimental and theoretical analyses reveal the orbital coupling between the catalytic iron center and the adjacent nickel atom, which leads to alteration in orbital energy level, unique electronic states, higher oxidation state of iron, and weakened binding strength to the reaction intermediates, thus boosted CO 2 RR and OER performance. This work provides critical insights to rational design, working mechanism, and application of hetero-DASCs. Diatomic site catalysts utilize two adjacent atomic metal species for their complementary functionalities and synergistic actions. Here, the authors report the orbital coupling of hetero-diatomic nickel-iron site boosts CO 2 reduction reaction and oxygen evolution reaction.

Seawater electroreduction is attractive for future H 2 production and intermittent energy storage, which has been hindered by aggressive Mg 2+ /Ca 2+ precipitation at cathodes and consequent poor stability. Here we present a vital microscopic bubble/precipitate traffic system (MBPTS) by constructing honeycomb-type 3D cathodes for robust anti-precipitation seawater reduction (SR), which massively/uniformly release small-sized H 2 bubbles to almost every corner of the cathode to repel Mg 2+ /Ca 2+ precipitates without a break. Noticeably, the optimal cathode with built-in MBPTS not only enables state-of-the-art alkaline SR performance (1000-h stable operation at –1 A cm −2 ) but also is highly specialized in catalytically splitting natural seawater into H 2 with the greatest anti-precipitation ability. Low precipitation amounts after prolonged tests under large current densities reflect genuine efficacy by our MBPTS. Additionally, a flow-type electrolyzer based on our optimal cathode stably functions at industrially-relevant 500 mA cm −2 for 150 h in natural seawater while unwaveringly sustaining near-100% H 2 Faradic efficiency. Note that the estimated price (~1.8 US$/kg H2 ) is even cheaper than the US Department of Energy’s goal price (2 US$/kg H2 ). Seawater electroreduction is a promising technique for producing hydrogen, but it is hindered by cathodic Mg2 + /Ca2+ precipitation. Here, the authors propose a microscopic bubble/precipitate traffic system that releases small-sized bubbles across the cathode to repel Mg2 + /Ca2+ precipitates from almost the entire surface area of the catalyst.