Boosting the Ni-Zn interplay via O/N dual coordination for high-efficiency CO_(2) electroreduction

Design of supportive atomic sites with a controllably adjusted coordinating environment is essential to advancing the reduction of CO_(2) to value-added fuels and chemicals and to achieving carbon neutralization.Herein,atomic Ni(Zn)sites that are uniquely coordinated with ternary Zn(Ni)/N/O ligands were successfully decorated on formamide-derived porous carbon nanomaterials,possibly forming an atomic structure of Ni(N_(2)O_(1))-Zn(N_(2)O_(1)),as studied by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.With the mediation of additional O coordination,the Ni-Zn dual site induces significantly decreased desorption of molecular CO.The NiZn-NC decorated with rich Ni(N_(2)O_(1))-Zn(N_(2)O_(1))sites remarkably gained>97%CO Faraday efficiency over a wide potential range of -0.8 to -1.1 V(relative to reversible hydrogen electrode).Density functional theory computations suggest that the N/O dual coordination effectively modulates the electronic structure of the Ni-Zn duplex and optimizes the adsorption and conversion properties of CO_(2) and subsequent intermediates.Different from the conventional pathway of using Ni as the active site in the Ni-Zn duplex,it is found that the Ni-neighboring Zn sites in the Ni(N_(2)O_(1))-Zn(N_(2)O_(1))coordination showed much lower energy barriers of the CO_(2) protonation step and the subsequent dehydroxylation step.

Confined synthesis of MoS_(2) with rich co-doped edges for enhanced hydrogen evolution performance

Activating MoS_(2) with atomic metal doping is promising to harvest desirable Pt-matched hydrogen evolution reaction(HER)catalytic performance.Herein,we developed an efficient method to access edgerich lattice-distorted MoS_(2) for highly efficient HER via in-situ sulphuration of atomic Co/Mo species that were well-dispersed in a formamide-derived N-doped carbonaceous(f-NC)substrate.Apart from others,pre-embedding Co/Mo species in f-NC controls the release of metal sources upon annealing in S vapor,grafting the as-made MoS_(2) with merits of short-range crystallinity,distorted lattices,rich defects,and more edges exposed.The content of atomic Co species embedded in MoS_(2) reaches up to 2.85 at.%,and its atomic dispersion has been systematically confirmed by using XRD,HRTEM,XPS,and XAS characterizations.The Co-doped MoS_(2) sample exhibits excellent HER activity,achieving overpotentials of 67 and155 m V at j=10 m A cm^(-2) in 1.0 M KOH and 0.5 M H_(2)SO_(4),respectively.Density functional theory simulations suggest that,compared with free-doping MoS_(2),the edged Co doping is responsible for the significantly improved HER activity.Our method,in addition to providing reliable Pt-matched HER catalysts,may also inspire the general synthesis of edge-rich metal-doped metal chalcogenide for a wide range of energy conversion applications.

Single-atom Zn for boosting supercapacitor performance

Single-atom metal-incorporated carbon nanomaterials(CMs)have shown great potential towards broad catalytic applications.In this work,we show that N-doped porous CMs embedded with redox-able Zn atoms exhibit superior capacitive performance.High Zn(~2.72 at.%)/N(~12.51 at.%)doping were realized by incorporating Zn2+and benzamide into the condensation and carbonization of formamide and subsequent annealing at 900℃.The Zn and N species are mutually benefited during the formation of ZnN4 motif.The as-obtained Zn1NC material affords a very large capacitance of 621 F·g^(−1)(at 0.1 A·g^(−1)),superior rate capability(~65%retention at 100 A·g^(−1)),and excellent cycling stability(0.00044%per cycle at 10 A·g^(−1)).These merits are attributed to the high Zn/N loading,atomic Zn-boosted pseudocapacitive behavior,large specific surface area(~1,085 m^(2)·g^(−1)),and rich pore hierarchy,thus ensuring both large pseudo-capacitance(e.g.,~37.9%at 10 mV·s^(−1))and double-layer capacitance.Besides of establishing a new type of high Zn/N-loading carbon materials,our work uncovers the capacitive roles of atomically dispersed metals in CMs.