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At present, formic acid with the high energy value is the promising product generated by the large-scale renewable electricity-driven CO 2 conversion, yet challenges remain in the high-throughput and low-energy production accompanied by the considerable selectivity. Herein, in view of the contribution of electronic modulation to electrocatalytic CO 2 reduction reaction (CO 2 RR) activity of catalysts, the thin BiCu-bimetallic film was designed and built on Cu foam (BiCu/CF) by coupling a facile hydrothermal reaction and an immediate electrochemical transformation. The theoretical evidences demonstrate that Bi p -orbital delocalization triggered by the close-contact metal Cu optimizes reaction pathway of CO 2 RR, and also favours the orbital hybridization between Bi atom and *OCHO intermediate to form more anti-bonding orbitals, resulting in stabilizing *OCHO intermediate and lowering the thermodynamic barrier of CO 2 RR. Meanwhile, the electron transferred from catalyst-sites to reaction species also accelerates during CO 2 RR. Integrating the improved intrinsic activity of Bi catalytic-sites and the superiority of Cu foam in exposing more active sites and the mechanical strength, the BiCu/CF electrode with optimal thickness can acquire satisfactory indicators for industrial application, yielding a record formate current density of 856 mA cm−2, higher than 85% Faradic efficiency, along with a remarkable stability, which outperforms state-of-the-art Bi-based catalysts. This study offers potential avenues of engineering orbital delocalization to rationally construct advanced CO 2 RR electrodes for the carbon-neutral cycle and utilization. Cu-triggered Bi p -orbital delocalization favours the orbital hybridization between Bi catalytic-sites and *OCHO intermediate and also lowers the thermodynamic barrier of CO 2 reduction. Therefore, BiCu-bimetallic film on Cu foam yields delightful current densities of 1000 mA cm−2 with HCOOH FEs larger than 85% as well as the remarkable catalytic stability and reproducibility, which are closer to the industrial demand. [Display omitted] • The optimal BiCu/CF yields a record formate current density of 856 mA cm−2 along with higher than 85% Faradic efficiency. • The delocalized Bi p -orbitals triggered by metal Cu reduce the thermodynamic and dynamic barrier of CO 2 reaction. • It is opening up a new perspective for engineering p -orbital delocalization of main-group metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • t f descriptor is proposed to predict the HER performance of perovskite catalysts. • Co d /O p -band centers well correlate with the HER activity of LnBaCo 2 O 5+ δ. • The descriptors produce highly active and stable perovskite catalysts. Herein the structural versatility is allowed to correlate with electrocatalytic properties of the perovskites. We report LnBaCo 2 O 5+ δ (Ln = lanthanide) perovskites as highly active electrocatalysts for hydrogen evolution reaction (HER). The tolerance factor (t f) and O p /Co d -band centers are proposed to be efficient descriptors for addressing their electrochemical performance. The t f endows the HER activity/stability with a volcano shape for our synthesized double/simple perovskites. The O p /Co d -band centers locating far from the Fermi level (E F) results in the best activity of LaBaCo 2 O 5+ δ among the LnBaCo 2 O 5+ δ perovskites. The outstanding stability can be explained by having the O p /Co d -band centers neither close to nor far from the E F. The maximum HER activity benefits from optimal free energy combination for the adsorption/dissociation of H 2 O and desorption of –OH/H*. The proper t f values and O p /Co d -band centers may realize synergistic interplay, which is crucial to reasonably design the oxide materials. [ABSTRACT FROM AUTHOR]

The easily coupled HER and OER catalysts are highly desired for the hydrogen evolution by overall water splitting. Here, we design and synthesize Co-Mo based catalysts with adjustable electronic structure by tuning the Mo/Co ratio to give easily coupled, effective HER/OER catalysts. At lower Mo/Co ratio, the Mo component can move up the d-band center of the catalysts, rendering an enhanced capability of activating H 2 O to improve OER performance with a low overpotential of 223 mV at 10 mA cm−2 (η 10). Contrastingly, the Co component in the catalyst with higher Mo/Co ratio can induce the downward shift of the d-band center, optimizing the Gibbs free energy of hydrogen adsorption to enhance the HER activity (a low η 10 of 52 mV). These HER and OER catalysts with similar components can be coupled for overall water splitting. The electrolyzer can be driven by a solar panel to achieve effective H 2 production. [Display omitted] • Co-Mo based catalysts with adjustable electronic structure were synthesized. • The adjustment of electronic structure can be realized by carefully tuning the Mo/Co ratio. • The change of Mo/Co ratio can regulate the structure of the catalysts as solid/hollow cubes. • The Co 6 Mo 6 C/MoC/Co catalysts exhibit good performance for HER (η 10 of 52 mV) and OER (η 10 of 223 mV). • The origin of HER performance of catalysts with different Co/Mo ratio is explained by DFT calculations. [ABSTRACT FROM AUTHOR]

The controllable construction of Fe,N co-doped carbon (Fe-N-C) nanocomposite has highly potential in replacing the noble metal catalysts. Herein, the Fe/N/P-tridoped expanded carbon nanotubes (P-Fe-N-CNTs) are prepared according to a simple one-step pyrolysis procedure. The unexpanded Fe-N-C carbon nanotubes (Fe u -N-CNTs) are also fabricated for comparision. The expanded P-Fe-N-CNTs yields a high half-wave potential (E 1/2) of 0.8843 V compared with unexpanded Fe u -N-CNT and commercial Pt/C. Furthermore, the expanded P-Fe-N-CNT as catalyst of Zn-air battery achieves high electrocatalytic performance, which is better than commercial Pt/C material. The unique architecture of expanded P-Fe-N-CNTs can improve the specific surface area and promote the formation the abundant active site, thus promoting the ORR kinetic process. Density functional theory (DFT) calculations futher confirm that suitable P doping can regulate the electronic structures of the active catalytic sites. The work provides a controllable way to prepare rational expanded P-Fe-N-CNTs for different applications, especially in Zn-air battery. [Display omitted] • The morphology of Fe/N/P-tridoped expanded carbon nanotubes are firstly regulated. • The suitable P dopant can optimize the electronic structures of active sites. • The expanded P-Fe-N-CNTs promotes the formation of abundant active site. • The P-Fe-N-CNTs catalyst shows high ORR performance. • The rational expanded P-Fe-N-CNTs exhibits a potential application prospect. [ABSTRACT FROM AUTHOR]