The organic-inorganic halide CH 3 NH 3 PbI 3 (MAPbI 3 ) has been the most commonly used light absorber layer of perovskite solar cells (PSCs); however, solution-processed MAPbI 3 films usually suffer from random crystal orientation and high trap density, resulting in inferior power conversion efficiency (PCE) with open circuit voltage (V oc ) being typically below 1.2 V for PSC devices. Herein, for the first time an imidazole sulfonate zwitterion, 4-(1H-imidazol-3-ium-3-yl)butane-1-sulfonate (IMS), is applied as a bifunctional additive in regular-structure planar heterojunction PSC devices to regulate the crystal orientation, yielding highly ordered MAPbI 3 film and passivating the trap states of the film. Such a dual effect of IMS is fulfilled via coordination interactions between the sulfonate moiety of IMS with the Pb2 + ion and the electrostatic interaction between the imidazole of IMS with the Iion of MAPbI 3 . As a result, under a optimized IMS doping ratio of 0.5 wt%, the PSC device exhibits a significant increase in PCE from 18.77% to 20.84%, with suppressed current-voltage hysteresis and promoted ambient stability. Moreover, a high V oc of 1.208 V is achieved under a higher IMS doping ratio of 1.2 wt%, which is the highest V oc for regular-structure MAPbI 3 planar PSC devices based on TiO 2 electron transport layer.

Two‐dimensional covalent organic frameworks (2D COFs), an emerging class of crystalline porous polymers, have been recognized as a new platform for efficient solar‐to‐hydrogen energy conversion owing to their pre‐designable structures and tailor‐made functions. Herein, we demonstrate that slight modulation of the chemical structure of a typical photoactive 2D COF (Py‐HTP‐BT‐COF) via chlorination (Py‐ClTP‐BT‐COF) and fluorination (Py‐FTP‐BT‐COF) can lead to dramatically enhanced photocatalytic H2 evolution rates (HER=177.50 μmol h−1 with a high apparent quantum efficiency (AQE) of 8.45 % for Py‐ClTP‐BT‐COF). Halogen modulation at the photoactive benzothiadiazole moiety can efficiently suppress charge recombination and significantly reduce the energy barrier associated with the formation of H intermediate species (H*) on polymer surface. Our findings provide new prospects toward design and synthesis of highly active organic photocatalysts toward solar‐to‐chemical energy conversion.

Covalent Organic Frameworks In their Research Article on page 16902, H. Xu, L. Chen et al. report on the modulation of benzothiadiazole‐based covalent organic frameworks through halogenation for enhanced photocatalytic water splitting.

Electrocatalytic water splitting has been one of the most promising routes for efficient H 2 production, which can work as a practical way to store the excess electricity generated by solar panel, wind, and nuclear reactor. Although platinum group Transition metal carbide compound has been extensively investigated as a catalyst for hydrogenation, for example, due to its noble metal-like properties. Herein a facile synthetic strategy is applied to control the thickness of atomiclayer Pt clusters strongly anchored on N-doped Mo 2 C nanorods (Pt/N-Mo 2 C) and it is found that the Pt atomic layers modify Mo 2 C function as a high-performance and robust catalyst for hydrogen evolution. The optimized 1.08 wt% Pt/N-Mo 2 C exhibits 25-fold, 10-fold, and 15-fold better mass activity than the benchmark 20 wt% Pt/C in neutral, acidic, and alkaline media, respectively. This catalyst also represents an extremely low overpotential of −8.3 mV at current density of 10 mA cm −2 , much better than the majority of reported electrocatalysts and even the commercial reference catalyst (20 wt%) Pt/C. Furthermore, it exhibits an outstanding long-term operational durability of 120 h. Theoretical calculation predicts that the ultrathin layer of Pt clusters on Mo-Mo 2 C yields the lowest absolute value of ΔG H* . Experimental results demonstrate that the atomic layer of Pt clusters anchored on Mo 2 C substrate greatly enhances electron and mass transportation efficiency and structural stability. These findings could provide the foundation for developing highly effective and scalable hydrogen evolution catalysts.

The interaction between photogenerated carriers with lattice vibrations plays a fundamental role in the nonradiative recombination and charge-transfer processes occurring in photocatalysis and photovoltaics. Here, we employ Raman spectroscopy to investigate the electron–phonon interaction in ternary layered Cu2MoS4 nanoflakes. Multiphonon Raman scattering with up to fourth-order longitudinal optical (LO) overtones is observed under above-band gap excitation, indicating a strong electron–phonon coupling (EPC) that could be described by the cascade model. The Huang–Rhys factor was derived to characterize the strength of EPC and was found to be increasing with decreasing temperature. First-principles calculations of lattice dynamics and electron–phonon matrix elements suggest that the strong EPC in Cu2MoS4 is dominated by Fröhlich coupling between electron and the electric fields, which is induced by the localized phonon mode originating from a flat phonon branch. Our findings facilitate the understanding of electron–phonon interaction in 2D ternary Cu2MoS4 and pave the way for developing and optimizing optoelectronic devices.

Single-atom catalysts (SACs) have drawn great attention in developing highly active and low-cost catalysts for electrocatalytic nitrogen reduction reaction (NRR) in ammonia synthesis, but the atomic metal centers are mainly limited to transition metals. Here, four stable alkaline-earth-metal (AEM)-based SACs are proposed by anchoring AEM on nitrogen-doped graphene nanoribbons, based on first-principles calculations. All SACs exhibit excellent NRR performance with competitive limiting potentials compared to stepped Ru (0001), and Ca-based SAC achieves optimal activity with a potential of −0.716 V. It is revealed that the low oxidation state of AEM is crucial for the activation of N 2 through an acceptance−backdonation mechanism. The antibonding 2π* orbital of N 2 can accept residual s electrons of low-valent AEM and backdonate electrons to the empty d orbitals of AEM, resulting in activation of N 2 molecules. In particular, the activation degree of N 2 and NRR activity is linearly associated with the charge states of AEMs. Our work reveals the underlying mechanism of AEMs for N 2 activation and reduction and presents the potential of AEM SACs as efficient electrochemical NRR catalysts.

The adjacent chemical microenvironment of single metal atoms in heterogeneous catalysis is crucial to their chemical activity for various catalytic processes. Here, based on firstprinciples calculations, 25 single transition metal atom catalysts coordinated to sulfur species embedded in graphene (TM-S 4 -G-SACs) are reported for nitrogen reduction under ambient condition. It shows that nine TM-S 4 -G-SACs (TM = Mo, Sc, Cr, V, W, Ti, Nb, Mn, and Re) are promising nitrogen reduction catalysts with an optimal potential of −0.425 V. Meanwhile, 18 TM-S 4 -G-SACs have better catalytic activity than those with nitrogen coordination. Particularly, the catalytic activity of TM-S 4 -G-SACs and the adsorption energy of intermediate NH 2 * conform to a volcano-type correlation, which can be described by a universal electronic descriptor φ, defined by the electronegativity of the metal, adjacent coordinated atoms, and the valence electron occupancy. The above findings suggest the potential of sulfur-coordinated single metal atoms as electrocatalytic nitrogen reduction catalysts and an applicable descriptor to achieve optimal performance.

A Cu2O(111)-like thin film with a honeycomb structure is grown on Pt(111) whose interface exhibits extremely high reactivity to CO molecules.