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Urea, an agricultural fertilizer, nourishes humanity. The century‐old Bosch–Meiser process provides the world's urea. It is multi‐step, consumes enormous amounts of non‐renewable energy, and has a large CO2 footprint. Thus, developing an eco‐friendly synthesis for urea is a priority. Herein we report a single‐step Pd/LTA‐3A catalyzed synthesis of urea from CO2 and NH3 under ambient conditions powered solely by solar energy. Pd nanoparticles serve the dual function of catalyzing the dissociation of NH3 and providing the photothermal driving force for urea formation, while the absorption capacity of LTA‐3A removes by‐product H2O to shift the equilibrium towards urea production. The solar urea conversion rate from NH3 and CO2 is 87 μmol g−1 h−1. This advance represents a first step towards the use of solar energy in urea production. It provides insights into green fertilizer production, and inspires the vision of sustainable, modular plants for distributed production of urea on farms. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction (PCR) is able to convert solar energy into chemicals, fuels, and feedstocks, but limited by the deficiencies of photocatalysts in steering photon-to-electron conversion and activating CO2, especially in pure water. Here we report an efficient, pure water CO2-to-CO conversion photocatalyzed by sub-3-nm-thick BiOCl nanosheets with van der Waals gaps (VDWGs) on the two-dimensional facets, a graphene-analog motif distinct from the majority of previously reported nanosheets usually bearing VDWGs on the lateral facets. Compared with bulk BiOCl, the VDWGs-rich atomic layers possess a weaker excitonic confinement power to decrease exciton binding energy from 137 to 36 meV, consequently yielding a 50-fold enhancement in the bulk charge separation efficiency. Moreover, the VDWGs facilitate the formation of VDWG-Bi-VO••-Bi defect, a highly active site to accelerate the CO2-to-CO transformation via the synchronous optimization of CO2 activation, *COOH splitting, and *CO desorption. The improvements in both exciton-to-electron and CO2-to-CO conversions result in a visible light PCR rate of 188.2 μmol g−1 h−1 in pure water without any co-catalysts, hole scavengers, or organic solvents. These results suggest that increasing VDWG exposure is a way for designing high-performance solar-fuel generation systems. Efficient CO2 photoreduction in pure water remains challenging. Here, the authors propose to use van der Waals gaps-rich BiOCl atomic layers with low exciton binding energy and abundant surface oxygen vacancies for CO2 to CO conversion. [ABSTRACT FROM AUTHOR]

Haber–Bosch thermal ammonia synthesis is of energy-intensive nature. Using solar energy for ammonia synthesis is idealized for both energy and environment problems, but remains great challenges. Generally, the diffuse solar flux and inefficient utilization cannot meet the energy demand for NH 3 production. Here we develop a solar thermal avenue, realizing highly efficient solar ammonia synthesis over K/Ru/TiO 2-x H x . The supported Ru is efficient for nitrogen activation because of the electron donation from TiO 2-x H x and free from H 2 poisoning, because the interfacial TiO 2-x H x accepts H atoms from Ru and then delivers them to the Ru activated N 2 to form Ti-NH x (x = 1–3) even at room temperature. When only irradiated with sunlight, this catalyst absorbs sunlight in the whole UV–vis-NIR region and reaches 360 °C by its plasmonic behavior, exhibiting a Haber–Bosch thermocatalysis-comparable NH 3 generation rate. This solar thermal approach with K/Ru/TiO 2-x H x provides a promising renewable way for ammonia synthesis. [ABSTRACT FROM AUTHOR]