Nickel is an essential nutrient for plants. However, the amount of Ni required for normal growth of plants is very low. Hence, with the level of Ni pollution in the environment increasing, it is essential to understand the functional roles and toxic effects of Ni in plants. We briefly review advances in relevant research over the past 20 years. Based on the available data, two new indirect pathways of Ni toxicity in plants are proposed. These are (i) interference with other essential metal ions and (ii) induction of oxidative stress. Research should focus on these mechanisms at the protein and molecular levels. Further research should also be directed at plant species that are capable of accumulating Ni at high concentration, so-called hyperaccumulators. Such species can provide model systems to study the mechanisms of Ni tolerance and can also be used for phytoremediation by removing nickel from polluted environment.
Passivation of electronic defects
on the surface and at grain boundaries
(GBs) of perovskite films has become one of the most effective tactics
to suppress charge recombination in perovskite solar cells. It is
demonstrated that trap states can be effectively passivated by Lewis
acid or base functional groups. In this work, nicotinamide (NTM, commonly
known as vitamin B3 or vitamin PP) serving as a Lewis base additive
is introduced into the PbI2 and/or FAI: MABr: MACl precursor
solution to obtain NTM modified perovskite films. It has been found
that the NTM in the perovskite film can well passivate surface and
GBs defects, control the film morphology and enhance the crystallinity
via its interaction with a lone pair of electrons in nitrogen. In
the presence of the NTM additive, we obtained enlarged perovskite
crystal grain about 3.6 μm and a champion planar perovskite
solar cell with efficiency of 21.72% and negligible hysteresis. Our
findings provide an effective route for crystal growth and defect
passivation to bring further increases on both efficiency and stability
of perovskite solar cells.
Electrocatalysis is a potential method for sustainable hydrogen production, and the development of non-noble metal-based effective electrocatalysts for electrochemical water splitting is the core of exploiting and utilizing renewable energy. Herein, a stupendous electrocatalyst with multiheterostructure interfaces and 3D porous structure is synthesized, and the mechanisms of enhanced electrocatalytic activity combining multicharacterizations and density functional calculations are clarified. Especially, the fabricated Co 2 P/N@Ti 3 C 2 T x @NF (denoted as CPN@TC) exhibits an ultralow overpotential of 15 mV to arrive at a current density of 10 mA cm −2 with the long-term durability and a small Tafel slope of 30 mV dec −1 in 1 m KOH, which even compares with noble metal catalysts favorably. The outstanding HER activity is ascribed to multiheterointerfaces for adsorbing H 2 O and H*, fine conductivity for the electronic transmission, and well-designed structure for rapid transport of ions and gases. It is reasonable to think that the synthetic strategy of CPN@TC can be extended to the preparation of transition-metal-based phosphides for enhanced catalytic performance.
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