The ideal charge transport materials should exhibit a proper energy level, high carrier mobility, sufficient conductivity, and excellent charge extraction ability. Here, a novel electron transport material was designed and synthesized by using a simple and facile solvothermal method, which is composed of the core−shell ZnO@SnO 2 nanoparticles. Thanks to the good match between the energy level of the SnO 2 shell and the high electron mobility of the core ZnO nanoparticles, the PCE of inorganic perovskite solar cells has reached 14.35% (J SC : 16.45 mA cm −2 , V OC : 1.11 V, FF: 79%), acting core−shell ZnO@SnO 2 nanoparticles as the electron transfer layer. The core−shell ZnO@SnO 2 nanoparticles size is 8.1 nm with the SnO 2 shell thickness of 3.4 nm, and the electron mobility is seven times more than SnO 2 nanoparticles. Meanwhile, the uniform core−shell ZnO@SnO 2 nanoparticles is extremely favorable to the growth of inorganic perovskite films. These preliminary results strongly suggest the great potential of this novel electron transfer material in high-efficiency perovskite solar cells.

We have created a facial self-templated method to synthesize three distinct nanostructures, including the unique edge-cut Cu@Ni nanocubes, edgenotched Cu@Ni nanocubes, and mesoporous Cu−Ni nanocages by selective wet chemical etching method. Moreover, in the synthesis process, the corners of edgecut Cu@Ni nanocubes and mesoporous Cu−Ni nanocages can be etched to produce the highly catalytically active (111) facets. Impressively, compared to edge-notched Cu@Ni nanocubes and edge-cut Cu@Ni nanocubes, the Cu−Ni nanocages exhibit higher electrocatalytic activity in the hydrogen evolution reaction (HER) under alkaline conditions. When obtained overpotential is 140 mV, the current density can reach 10 mA cm −2 ; meanwhile, the corresponding Tafel slope is 79 mV dec −1 . Moreover, from the calculation results of density functional theory (DFT), it can be found that the reason why the activity of pure Ni is lower than that of Cu−Ni alloy is that the adsorption energy of the intermediate state (adsorbed H*) is too strong. Meanwhile the Gibbs free-energy (|ΔG H* |) of (111) facets is smaller than that of (100) facets, which brings more active sites or adsorbs more hydrogen.

Oxygen evolution reaction (OER) is a pivotal step for many sustainable energy technologies, and exploring inexpensive and highly efficient electrocatalysts is one of the most crucial but challenging issues to overcome the sluggish kinetics and high overpotentials during OER. Among the numerous electrocatalysts, metal-organic frameworks (MOFs) have emerged as promising due to their high specific surface area, tunable porosity, and diversity of metal centers and functional groups. It is believed that combining MOFs with conductive nanostructures could significantly improve their catalytic activities. In this study, an MXene supported CoNi-ZIF-67 hybrid (CoNi-ZIF-67@Ti3C2Tx) was synthesized through the in-situ growth of bimetallic CoNi-ZIF-67 rhombic dodecahedrons on the Ti3C2Tx matrix via a coprecipitation reaction. It is revealed that the inclusion of the MXene matrix not only produces smaller CoNi-ZIF-67 particles, but also increases the average oxidation of Co/Ni elements, endowing the CoNi-ZIF-67@Ti3C2Tx as an excellent OER electrocatalyst. The effective synergy of the electrochemically active CoNi-ZIF-67 phase and highly conductive MXene support prompts the hybrid to process a superior OER catalytic activity with a low onset potential (275 mV vs. a reversible hydrogen electrode, RHE) and Tafel slope (65.1 mV∙dec−1), much better than the IrO2 catalysts and the pure CoNi-ZIF-67. This work may pave a new way for developing efficient non-precious metal catalyst materials.

A novel FeNC/MXene hybrid nanosheet with a rugged FeNC coating closely attached on the MXene surface was explored, which exhibited remarkable electrocatalytic activity with a superb durability (only 2.6% decay after a 20 000 s continuous test).

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