Na Yang

Abstract NiFe‐layered double hydroxides (NiFe‐LDH) are among the most active catalysts developed to date for the oxygen evolution reaction (OER) in alkaline media, though their long‐term OER stability remains unsatisfactory. Herein, we reveal that the stability degradation of NiFe‐LDH catalysts during alkaline OER results from a decreased number of active sites and undesirable phase segregation to form NiOOH and FeOOH, with metal dissolution underpinning both of these deactivation mechanisms. Further, we demonstrate that the introduction of cation‐vacancies in the basal plane of NiFe LDH is an effective approach for achieving both high catalyst activity and stability during OER. The strengthened binding energy between the metals and oxygen in the LDH sheets, together with reduced lattice distortions, both realized by the rational introduction of cation vacancies, drastically mitigate metal dissolution from NiFe‐LDH under high oxidation potentials, resulting in the improved long‐term OER stability. In addition, the cation vacancies (especially M 3+ vacancies) accelerate the evolution of surface γ‐(NiFe)OOH phases, thereby boosting the OER activity. The present study highlights that tailoring atomic cation‐vacancies is an important strategy for the development of active and stable OER electrocatalysts.

Abstract Atomically dispersed Zn–N–C nanomaterials are promising platinum‐free catalysts for the oxygen reduction reaction (ORR). However, the fabrication of Zn–N–C catalysts with a high Zn loading remains a formidable challenge owing to the high volatility of the Zn precursor during high‐temperature annealing. Herein, we report that an atomically dispersed Zn–N–C catalyst with an ultrahigh Zn loading of 9.33 wt % could be successfully prepared by simply adopting a very low annealing rate of 1° min −1 . The Zn–N–C catalyst exhibited comparable ORR activity to that of Fe–N–C catalysts, and significantly better ORR stability than Fe–N–C catalysts in both acidic and alkaline media. Further experiments and DFT calculations demonstrated that the Zn–N–C catalyst was less susceptible to protonation than the corresponding Fe–N–C catalyst in an acidic medium. DFT calculations revealed that the Zn–N 4 structure is more electrochemically stable than the Fe–N 4 structure during the ORR process.

Abstract Heterostructures composed of two‐dimensional black phosphorus (2D BP) with unique physical/chemical properties are of great interest. Herein, we report a simple solvothermal method to synthesize in‐plane BP/Co 2 P heterostructures for electrocatalysis. By using the reactive edge defects of the BP nanosheets as the initial sites, Co 2 P nanocrystals are selectively grown on the BP edges to form the in‐plane BP/Co 2 P heterostructures. Owing to disposition on the original defects of BP, Co 2 P improves the conductivity and offers more active electrocatalytic sites, so that the BP/Co 2 P nanosheets exhibit better and more stable electrocatalytic activities in the hydrogen evolution and oxygen evolution reactions. Our work not only extends the application of BP to electrochemistry, but also provides a new idea to improve the performance of BP by utilization of defects. Furthermore, this strategy can be extended to produce other BP heterostructures to expand the corresponding applications.

Abstract Electrochemical reduction of carbon dioxide (CO 2 ) is a promising approach to solve both renewable energy storage and carbon‐neutral energy cycles, while the capability of selective reduction to C 2+ products has still been quite limited. In this work, partially reduced copper oxide nanodendrites with rich surface oxygen vacancies (CuO x –Vo) are developed, serving as excellent Lewis base sites for enhanced CO 2 adsorption and subsequent electrochemical reduction. Theoretical calculations reveal that these oxygen vacancy‐rich CuO x surfaces provide strong binding affinities to the intermediates of *CO and *COH, but weak affinity to *CH 2 , thus leading to efficient formation of C 2 H 4 . As a result, the partially reduced CuO x nanodendrites exhibit one of the highest C 2 H 4 production Faradaic efficiencies of 63%. The electrochemical stability test further shows that the C 2 H 4 Faradaic efficiency strongly depends on the oxygen vacancy density in CuO x , which can further be regenerated for several cycles, thus suggesting the critical role of oxygen vacancies for the C 2 product selectivity.