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According to the d-band center theory of transition-metals, s-block main group metals with fewer valence electrons and delocalized s/p-orbitals are considered to exhibit poor electrocatalytic activity. Therefore, single-atom catalysts (SACs) for CO2 electroreduction to CO primarily focus on transition metal and p-block main group metal atoms as active centers. Herein, we prepared a porous carbon material doped with N/O coordinated K atoms using a simple high-temperature solid-phase synthesis method. The synthesized K–N, O/C catalyst demonstrates remarkable CO selectivity with Faraday efficiency (FE) exceeding 90% over a wide potential window between −0.5 V and −0.9 V versus the reversible hydrogen electrode (vs. RHE). Moreover, the catalyst exhibits a maximum FE of 97.8% towards CO at −0.6 V vs. RHE. In situ attenuated total reflectance infrared spectroscopy (ATR-FTIR) confirms the formation of *COOH on the K–N, O/C catalysts. Through Density Functional Theory (DFT) calculations, we screen out the most possible coordination structures. The K–O2 and K-pyrrolic-N2 models show significantly high CO2 reduction activity. Heteroatom doping induces partial overlap of the electronic states of the s and p orbitals of the K atom with the p orbitals of the coordinated O atom or N atom, thus modulating the electronic structure of the K atom into the catalytically active center for the conversion of CO2 to CO. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 to HCOOH is considered one of the most appealing routes to alleviate the energy crisis and close the anthropogenic CO2 cycle. However, it remains challenging to develop electrocatalysts with high activity and selectivity towards HCOOH in a wide potential window. In this regard, Ag/Bi2O2CO3 was prepared by an in situ electrochemical transformation from Ag/Bi2O3. The Ag/Bi2O2CO3 catalyst achieves a faradaic efficiency (FE) of over 90% for HCOOH in a wide potential window between −0.8 V and −1.3 V versus the reversible hydrogen electrode (RHE). Moreover, a maximum FE of 95.8% and a current density of 15.3 mA cm−2 were achieved at a low applied potential of −1.1 V. Density functional theory (DFT) calculations prove that the high catalytic activity of Ag/Bi2O2CO3 is ascribed to the fact that Ag can regulate the electronic structure of Bi, thus facilitating the adsorption of *OCHO and hindering the adsorption of *COOH. This work expands the in situ electrochemical derivatization strategy for the preparation of electrocatalysts. [ABSTRACT FROM AUTHOR]

As an external field, a magnetic field can change the electrocatalytic activity of catalysts through various effects. Among them, electron spin polarization on the catalyst surface has attracted much attention. Herein, we investigate the sensitive response behavior of a Cu2O nanocubes to an in situ magnetic field. Under a 3 T strong magnetic field, the total transferred electron quantity in IT test (−1.1 VRHE) and the current density in the polarization curve increase by 28.7% and 54.7%, respectively, while the onset potential decreases significantly by 114 mV. Moreover, it was found that product selectivity was also altered by the magnetic field. The Faraday efficiency of C1 increases substantially, along with the inhibition of C2+ reaction paths and the HER. Our experimental results and DFT calculation demonstrate that a hybrid magnetic effect accelerates the CO2RR kinetic and generates spin polarization of the catalyst surface. The polarized surface changes the binding energy of *OCHO/*COOH and inhibits singlet C–C coupling, which restrains the C2+ reduction path and thus more CO2 is reduced to HCOOH. [ABSTRACT FROM AUTHOR]

Designing robust catalysts for increasing the sluggish kinetics of the urea oxidation reaction (UOR) is challenging. Herein, the regulation of spin states for metal active sites by photoexcitation to facilitate the adsorption of urea and intermediates is demonstrated. Mo-doped nickel sulfide nanoribbon arrays (Mo-Ni 3 S 2 @NMF) with excellent light-trapping capacity are successfully prepared. Under AM 1.5G illumination, the activity of the Mo-Ni 3 S 2 @NMF exhibits a 50% improvement in the UOR current. Compared with those under dark conditions, Mo-Ni 3 S 2 @NMF achieve 10 mA cm -2 at 1.315 V RHE for UOR and 1.32 V cell for urea electrolysis, which are decreases of 15 and 80 mV, respectively. The electron spin resonance, in situ Fourier transform infrared spectroscopy analysis and density functional theory calculations reveal that illumination led to the formation of Ni 3+ active sites in a high-spin state, which strengthens the d-p orbital hybridization of Ni-N, hence facilitating the adsorption of urea. C─N cleavage of the * CONN intermediate is further inhibited, which promotes the oxidation of urea molecules via the active N 2 pathway, thereby accelerating the UOR rate., (© 2024 Wiley‐VCH GmbH.)

The electrocatalytic urea oxidation reaction (UOR) provides a promising alternative to the oxygen evolution reaction (OER) for various renewable energy-related systems owing to its lower thermodynamic barriers. However, its optimization and commercial utilization were hampered due to a lack of mechanistic understanding. Here, we demonstrate a Ce-doped Ni 3 S 2 catalyst supported on Ni foam (Ce-Ni 3 S 2 /NF) with superior activity toward UOR. The resultant Ce-Ni 3 S 2 /NF catalyst exhibits a lower Tafel slope of 20.3 mV dec -1 , a higher current density of 100 mA cm -2 at 1.39 V versus RHE, and better durability than those for Ni 3 S 2 /NF. Based on in situ synchrotron radiation X-ray absorption spectroscopy, in situ Fourier transform infrared (FTIR), and in situ Raman spectroscopy, we observe the structural reconstruction of sulfide and identify the adsorbed intermediates during UOR. Density functional theory (DFT) calculations reveal that Ce can regulate the electronic structure of Ni through Ce(4f)-O(2p)-Ni(3d) orbital electronic coupling. The modulated Ni sites have weaker adsorption of carbonaceous intermediates, thus accelerating the UOR. This work provides a promising route for the design of high-activity UOR catalysts.

The electrochemical reduction of CO 2 to HCOOH is considered one of the most appealing routes to alleviate the energy crisis and close the anthropogenic CO 2 cycle. However, it remains challenging to develop electrocatalysts with high activity and selectivity towards HCOOH in a wide potential window. In this regard, Ag/Bi 2 O 2 CO 3 was prepared by an in situ electrochemical transformation from Ag/Bi 2 O 3 . The Ag/Bi 2 O 2 CO 3 catalyst achieves a faradaic efficiency (FE) of over 90% for HCOOH in a wide potential window between -0.8 V and -1.3 V versus the reversible hydrogen electrode (RHE). Moreover, a maximum FE of 95.8% and a current density of 15.3 mA cm -2 were achieved at a low applied potential of -1.1 V. Density functional theory (DFT) calculations prove that the high catalytic activity of Ag/Bi 2 O 2 CO 3 is ascribed to the fact that Ag can regulate the electronic structure of Bi, thus facilitating the adsorption of *OCHO and hindering the adsorption of *COOH. This work expands the in situ electrochemical derivatization strategy for the preparation of electrocatalysts.

The clinical performance and failure issues are significantly influenced by prosthetic malposition in unicompartmental knee arthroplasty (UKA). Uncertainty exists about the impact of the prosthetic joint line height in UKA on tibial insert wear. In this study, we combined the UKA musculoskeletal multibody dynamics model, finite element model and wear model to investigate the effects of seven joint line height cases of fixed UKA implant on postoperative insert contact mechanics, cumulative sliding distance, linear wear depth and volumetric wear. As the elevation of the joint line height in UKA, the medial contact force and the joint anterior-posterior translation during swing phase were increased, and further the maximum von Mises stress, contact stress, linear wear depth, cumulative sliding distance, and the volumetric wear also were increased. Furthermore, the wear area of the insert gradually shifted from the middle region to the rear. Compared to 0 mm joint line height, the maximum linear wear depth and volumetric wear were decreased by 7.9% and 6.8% at -2 mm joint line height, and by 23.7% and 20.6% at -6 mm joint line height, the maximum linear wear depth and volumetric wear increased by 10.7% and 5.9% at +2 mm joint line height, and by 24.1% and 35.7% at +6 mm joint line height, respectively. UKA prosthetic joint line installation errors can significantly affect the wear life of the polyethylene inserted articular surfaces. Therefore, it is conservatively recommended that clinicians limit intraoperative UKA joint line height errors to -2-+2 mm.