Photocatalytic carbon dioxide (CO₂) to carbon monoxide (CO) offers a promising way for both alleviating the greenhouse effect and meeting the industrial demand. Herein, we constructed a Co single-atom catalyst with intentional low-coordination environment design on porous ZnO (denoted as Co₁/ZnO). Impressively, Co₁/ZnO exhibited a remarkable activity with a CO yield rate of 22.25 mmol·g⁻¹·h⁻¹ and a selectivity of 80.2% for CO₂ photoreduction reactions under visible light. The incorporation of single Co atoms provided an additional photo-generated electron transfer channel, which suppressed the carrier recombination of photocatalysts. Moreover, the unsaturated Co active sites were capable to adsorb CO₂ molecule spontaneously, thus facilitating the activation of CO₂ molecule during CO₂ reduction course.

Ammonia borane (AB) is regarded as a promising chemical hydrogen-storage material due to its high hydrogen content, non-toxicity, and long-term stability under ambient temperature. However, constructing advanced catalysts to further promote the hydrogen production still remains a challenge for the hydrolysis of AB. Herein, we report a novel oxygen modified CoP₂ (O-CoP₂) material with dispersed palladium nanoparticles (Pd NPs) as a highly efficient and sustainable catalyst for AB hydrolysis. The modification of oxygen could optimize the catalytic synergy effect between CoP₂ and Pd NPs, achieving enhanced catalytic activity with a turnover frequency (TOF) number of 532 min⁻¹ and an activation energy (E_a) value of 16.79 kJ·mol⁻¹. Meanwhile, reaction kinetic experiments prove that the activation of water is the rate-determining step (RDS). The water activation mechanism is revealed by quasi in-situ X-ray photoelectron spectroscopy (XPS) and in-situ X-ray absorption fine structure (XAFS) measurements. The activation of water leads to the production of –H and –OH groups, which are further adsorbed on the oxygen atoms in P–O bond and Pd atoms, respectively. In addition, density functional theory (DFT) calculations indicate that the introduced oxygen facilitates the adsorption and activation of water molecules. This novel modulation strategy successfully sheds new light on the development of advanced catalysts for hydrolysis of AB and beyond.

Designing active sites and engineering electronic properties of heterogeneous catalysts are both promising strategies that can be employed to enhance the catalytic activity for CO₂ hydrogenation. Herein, we report RhCo porous nanospheres with a high density of accessible grain boundaries as active sites for improved catalytic performance in the hydrogenation of CO₂ to methanol. The porous nanosphere morphological feature allows for a high population of grain boundaries to be accessible to the reactants, thereby providing sufficient active sites for the catalytic reaction. Moreover, in-situ X-ray photoelectron spectroscope (XPS) results revealed the creation of negatively charged Rh surface atoms that promoted the activation of CO₂ to generate CO₂^δ– and methoxy intermediates. The obtained RhCo porous nanospheres exhibited remarkable low-temperature catalytic activity with a turnover frequency (TOF_Rh) of 612 h^–1, which was 6.1 and 2.5 times higher than that of Rh/C and RhCo nanoparticles, respectively. This work not only develops an efficient catalyst for CO₂ hydrogenation, but also demonstrates a potential approach for the modulation of active sites and electronic properties.