Ammonia is a suitable hydrogen carrier with each molecule accounting for up to 17.65% of hydrogen by mass. Among various potential ammonia production methods, we adopt the photoelectrochemical (PEC) technique, which uses solar energy as well as electricity to efficiently synthesize ammonia under ambient conditions. In this article, we report MoS 2 @La 2 Zr 2 O 7 heterostructures designed by incorporating twodimensional (2D)-MoS 2 nanoflakes on La 2 Zr 2 O 7 nanofibers (MoS 2 @LZO) as photoelectrocatalysts. The MoS 2 @LZO heterostructures are synthesized by a facile hydrothermal route with electrospun La 2 Zr 2 O 7 nanofibers and Mo precursors. The MoS 2 @LZO heterostructures work synergistically to amend the drawbacks of the individual MoS 2 electrocatalysts. In addition, the harmonious activity of the mixed phase of pyrochlore/ defect fluorite-structured La 2 Zr 2 O 7 nanofibers generates an interface that aids in increased electrocatalytic activity by enriching oxygen vacancies in the system. The MoS 2 @LZO electrocatalyst exhibits an enhanced Faradaic efficiency and ammonia yield of approximately 2.25% and 10.4 μg h −1 cm −2 , respectively, compared to their corresponding pristine samples. Therefore, the mechanism of improving the PEC ammonia production performance by coupling oxygen-vacant sites to the 2D-semiconductorbased electrocatalysts has been achieved. This work provides a facile strategy to improve the activity of PEC catalysts by designing an efficient heterostructure interface for PEC applications.
Hydrogen has become an indispensable aspect of sustainable energy resources due to depleting fossil fuels and increasing pollution. Since hydrogen storage and transport is a major hindrance to expanding its applicability, green ammonia produced by electrochemical method is sourced as an efficient hydrogen carrier. Several heterostructured electrocatalysts are designed to achieve significantly higher electrocatalytic nitrogen reduction (NRR) activity for electrochemical ammonia production. In this study, we controlled the nitrogen reduction performances of Mo2C-Mo2N heterostructure electrocatalyst prepared by a simple one pot synthesis method. The prepared Mo2C-Mo2N0.92 heterostructure nanocomposites show clear phase formation for Mo2C and Mo2N0.92, respectively. The prepared Mo2C-Mo2N0.92 electrocatalysts deliver a maximum ammonia yield of about 9.6 μg h-1 cm-2 and a Faradaic efficiency (FE) of about 10.15%. The study reveals the improved nitrogen reduction performances of Mo2C-Mo2N0.92 electrocatalysts due to the combined activity of the Mo2C and Mo2N0.92 phases. In addition, the ammonia production from Mo2C-Mo2N0.92 electrocatalysts is intended by the associative nitrogen reduction mechanism on Mo2C phase and by Mars-van-Krevelen mechanism on Mo2N0.92 phase, respectively. This study suggests the importance of precisely tuning the electrocatalyst by heterostructure strategy to substantially achieve higher nitrogen reduction electrocatalytic activity.
Electrochemical water splitting is the eco‐friendly route to generate green hydrogen, which is recognized as sustainable energy for the future. However, the cost, operational efficiency, and long‐term durability of the electrochemical water splitting rely on the choice of the electrocatalysts. Hence, developing a superior design strategy is an important criterion to establish an efficient and sustainable water splitting system. Herein, a sulphur‐rich CoNiO heterostructure encapsulated on N‐rich carbon nanofibers (SCNO@N‐CNF) synthesized via a simple and efficient electrospinning technique is reported. The three‐way redox active centers, viz., the electron redistributed active Coδ ‐NiOδ + interfaces, S‐dopant sites with modified electronic density, and the porous N‐CNF matrix, makes the prepared electrocatalyst more efficient toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The SCNO@N‐CNF electrocatalyst exhibits a low OER and HER overpotentials (ηOER = 247 mV; ηHER = 169 mV) at a current density of 10 mA cm−2. Moreover, SCNO@N‐CNF was analyzed as the bifunctional electrocatalyst in overall electrochemical water splitting, and it is found to deliver 10 mA cm−2 at only 1.58 V. Thus, the design and engineering of multiple active elements in a single electrocatalyst is anticipated as an effective approach to establish an efficient and sustainable water splitting system.
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