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Scaling up quantum dots to two-dimensional (2D) arrays is a crucial step for advancing semiconductor quantum computation. However, maintaining excellent tunability of quantum dot parameters, including both nearest-neighbor and next-nearest-neighbor couplings, during 2D scaling is challenging, particularly for silicon quantum dots due to their relatively small size. Here, we present a highly controllable and interconnected 2D quantum dot array in planar silicon, demonstrating independent control over electron fillings and the tunnel couplings of nearest-neighbor dots. More importantly, we also demonstrate the wide tuning of tunnel couplings between next-nearest-neighbor dots, which play a crucial role in 2D quantum dot arrays. This excellent tunability enables us to alter the coupling configuration of the array as needed. These results open up the possibility of utilizing silicon quantum dot arrays as versatile platforms for quantum computing and quantum simulation.

Separating ethane (C 2 H 6 ) from ethylene (C 2 H 4 ) is an essential and energy-intensive process in the chemical industry. Here, we report two flexible diamondoid coordination networks, X-dia-1-Ni and X-dia-1-Ni 0.89 Co 0.11 , that exhibit gate-opening between narrow-pore (NP) and large-pore (LP) phases for C 2 H 6 , but not for C 2 H 4 . X-dia-1-Ni 0.89 Co 0.11 thereby exhibited a type F-IV isotherm at 273 K with no C 2 H 6 uptake and a high uptake (111 cm 3 g -1 , 1 atm) for the NP and LP phases, respectively. Conversely, the LP phase exhibited a low uptake of C 2 H 4 (12.2 cm 3 g -1 ). This C 2 H 6 /C 2 H 4 uptake ratio of 9.1 for X-dia-1-Ni 0.89 Co 0.11 far surpassed those of previously reported physisorbents, many of which are C 2 H 4 -selective. In situ variable-pressure X-ray diffraction and modeling studies provided insight into the abrupt C 2 H 6 -induced structural NP to LP transformation. The promise of pure gas isotherms and, more generally, flexible coordination networks for gas separations was validated by dynamic breakthrough studies, which afforded high-purity (99.9%) C 2 H 4 in one step.

The capture and separation of fluorinated gases (F-gases) from N 2 has the potential to not only reduce greenhouse gas emissions but also provide economic benefits for the semiconductor industry. In this work, two Ni-based metal-organic frameworks (MOFs), Ni-MOF (Ni(ina) 2 , ina = isonicotinic acid) and amine-functionalized NH 2 -Ni-MOF (Ni(3-ain) 2 , 3-ain = 3-aminoisonicotinic acid), were constructed for capturing F-gases (CF 4 and NF 3 ). At ambient conditions, both materials exhibit very high CF 4 sorption capacities (2.92 mmol g -1 for Ni-MOF and 2.69 mmol g -1 for NH 2 - Ni-MOF) . In addition, NH 2 -Ni-MOF exhibited a record selectivity of 46.3 for the CF 4 /N 2 mixture at 298 K and 100 kPa, surpassing all benchmark adsorbents, including Ni-MOF (34.7). The kinetic adsorption tests demonstrated that Ni-MOF and NH 2 -Ni-MOF performed well for CF 4 /N 2 and NF 3 /N 2 mixtures. According to grand canonical Monte Carlo (GCMC) simulations, CF 4 or NF 3 interacts with NH 2 -Ni-MOF by multiple van der Waals interactions, resulting in stronger interaction than N 2 . More importantly, dynamic breakthrough experiments verified the practical separation potential of the two materials for CF 4 /N 2 and NF 3 /N 2 mixtures.