An SAC Pt/g-C3N4 enables significant deviation from the scaling between the energetics of *N2H and *NH2, promising for ambient electrochemical NH3 synthesis.

h i g h l i g h t s g r a p h i c a l a b s t r a c tNanoparticles of LiMnPO 4 were fabricated in rod, elongated as well as cubic shapes. The 1D Li þ preferred diffusion direction for each shape was determined via electron diffraction spot patterns. The shape of nano-LiMnPO 4 varied the diffusion coefficient of Li þ because the Li þ diffusion direction and the path length were different. The particles with the shortest dimension along the b-axis provided the highest diffusion coefficient, resulting in the highest gravimetric capacity of 135, 100 and 60 mAh g À1 at 0.05C, 1C and 10C, respectively. Using ball-milling, a higher loading of nano-LiMnPO 4 in the electrode was achieved, increasing the volumetric capacity to 263 mAh cm À3 , which is ca. 3.5 times higher than the one obtained by hand-mixing of electrode materials. Thus, the electrochemical performance is governed by both the diffusion coefficient of Li þ , which is dependent on the shape of LiMnPO 4 nanoparticles and the secondary composite structure.

We use first-principles calculations to systematically explore the potential of transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) embedded in buckled monolayer g-CN as single-atom catalysts. We show that clustering of Sc and Ti on g-CN is thermodynamically impeded and that V, Cr, Mn, and Cu are much less susceptible to clustering than the other TM atoms under investigation. Strong bonding of the transition metal atoms in the cavities of g-CN and high diffusion barriers together are responsible for single-atom fixation. Analysis of the CO oxidation process indicates that embedding of Cr and Mn in g-CN gives rise to promising single-atom catalysts at low temperature.

The development of earth-abundant electrocatalysts with high intrinsic activity, abundant active sites, and good electrical conductivity is of vital importance for the market penetration of clean energy technologies. We herein report a facile synthesis of a self-supported Co2N/CoN/Co2Mo3O8 heterostructured catalyst on cobalt foam (CF) by a hydrothermal process followed by nitridation treatment. Our first-principles calculations revealed that Co2Mo3O8 and Co2N could work in concert to provide active sites for an alkaline hydrogen evolution reaction (HER). The hierarchical and nanoporous architecture of the Co2N/CoN/Co2Mo3O8 catalyst ensured an abundance of accessible active sites. The direct growth of metalloid Co x N nanoparticles on the defective Co2Mo3O8 substrate endowed the catalyst with good electrical conductivity. As a consequence, the Co2N/CoN/Co2Mo3O8/CF catalyst showed extraordinarily high activity and good stability toward the alkaline HER, outperforming most existing non-precious electrocatalysts. In particular, it exhibited a comparable catalytic performance to the commercial Pt/C catalyst at a current density of 100 mA cm–2.