Photocorrosion is a key factor that greatly hinders the stability of photoanodes. Depositing appropriate cocatalysts can effectively protect the semiconductors from photocorrosion as well as improve the photoelectrochemical (PEC) activity. However, the formation of cocatalysts occurs mostly under island growth, making the semiconductors partially unprotected, thus leading to poor stability. Herein, we demonstrate the complex assembly film composed of phenolic ligands (tannic acid) coordinated with Ni and Fe ions (TANF) as a robust cocatalyst for Mo-doped BiVO4 (Mo:BiVO4@TANF) toward PEC water oxidation. The photocurrent density of Mo:BiVO4@TANF at 1.23 V versus reversible hydrogen electrode (RHE) reaches a value of 5.10 ± 0.13 mA cm–2. Furthermore, because the complete coverage of the TANF film can effectively protect the semiconductor from photocorrosion, 92% photocurrent of the integrated photoanode is retained after operating at harsh 1.23 V vs RHE for 3 h. The outstanding activity and stability of the integrated photoanode surpass those of many existing cocatalysts such as ferrihydrite (Fh) and cobalt phosphate (Co-Pi). In addition, the TANF cocatalyts can be also applied to other semiconductors (nondoped BiVO4 and TiO2), indicating the TANF is a promising cocatalyst alternative for solar energy conversion.

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Electrocatalytic reduction of CO2 by metal–organic frameworks (MOFs) has been widely investigated, but insufficient conductivity limits application. Herein, a porous 3D In‐MOF {(Me2NH2)[In(BCP)]⋅2 DMF}n (V11) with good stability was constructed with two types of channels (1.6 and 1.2 nm diameter). V11 exhibits moderate catalytic activity in CO2 electroreduction with 76.0 % of Faradaic efficiency for formate (FEHCOO‐). Methylene blue molecules of suitable size and pyrolysis temperature were introduced and transformed into carbon particles (CPs) after calcination. The performance of the obtained CPs@V11 is significantly improved both in FEHCOO‐ (from 76.0 % to 90.1 %) and current density (2.2 times). Control experiments show that introduced CPs serve as accelerant to promote the charges and mass transfer in framework, and benefit to sufficiently expose active sites. This strategy can also work on other In‐MOFs, demonstrating the universality of this method for electroreduction of CO2.

Developing efficient catalytic materials and unveiling the active species are significant for selective hydrogenation of CO2 to C2+ hydrocarbons. Fe2N@C nanoparticles were reported to exhibit outstanding performance toward selective CO2 hydrogenation to C2+ hydrocarbons (C2+ selectivity: 53.96 %; C2‐C4= selectivity, 31.03 %), outperforming corresponding Fe@C. In situ X‐ray diffraction, ex situ Mössbauer and X‐ray photoelectron spectra revealed that iron nitrides were in situ converted to highly active iron carbides, which acted as the real active species. Moreover, the combined results of in situ diffuse reflectance infrared Fourier transform spectroscopy and control experiments suggested an in situ formed carbonyl iron‐mediated conversion mechanism from iron nitrides to iron carbides.

Conspectus The hydrogenation reaction is one of the most frequently used transformations in organic synthesis. Electrocatalytic hydrogenation by using water (H2O) as the hydrogen source offers an efficient and sustainable approach to synthesize hydrogenated products under ambient conditions. Such a technique can avoid the use of high-pressure and flammable hydrogen gas or other toxic/expensive hydrogen donors, which usually cause environmental, safety, and cost concerns. Interestingly, utilizing easily available heavy water (D2O) for deuterated syntheses is also attractive due to the widespread applications of deuterated molecules in organic synthesis and the pharmaceutical industry. Despite impressive achievements, electrode selection mainly relies on trial-and-error modes, and how electrodes dictate reaction outcomes remains elusive. Therefore, the rational design of nanostructured electrodes for driving the electrocatalytic hydrogenation of a series of organics via H2O electrolysis is developed. In this Account, we review recent advances in the electrocatalytic hydrogenation of different types of organic functional groups, including CC, CN, CC, CO, and C–Br/I bonds, −NO2, and N-heterocycles, with H2O over nanostructured cathodes. First, the general reaction steps (reactant/intermediate adsorption, active atomic hydrogen (H*) formation, surface hydrogenation reaction, product desorption) are analyzed, and key factors are proposed to optimize hydrogenation performance (e.g., selectivity, activity, Faradaic efficiency (FE), reaction rate, and productivity) and inhibit side reactions. Then, ex situ and in situ spectroscopic tools to study key intermediates and interpret mechanisms are introduced. Third, based on the knowledge of key reaction steps and mechanisms, we introduce catalyst design principles in detail on how to optimize the adoption of reactants and key intermediates, promote the formation of H* from water electrolysis, inhibit hydrogen evolution and side reactions, and improve the selectivity, reaction rate, FEs, and space-time productivity of products. We then introduce some typical examples. (i) P- and S-modified Pd can decrease CC adsorption and promote H* formation, enabling semihydrogenation of alkynes with high selectivity and FEs at lower potentials. Then, creating high-curvature nanotips to concentrate the substrates further speeds up the hydrogenation process. (ii) By introducing low-coordination sites into Fe and combining low-coordination sites and surface fluorine to modify Co to optimize the adsorption of intermediates and facilitate H* formation, hydrogenation of nitriles and N-heterocycles with high activity and selectivity is obtained. (iii) By forming isolated Pd sites to induce a specific σ-alkynyl adsorption of alkynes and steering S vacancies of Co3S4–x to preferentially adsorb −NO2, hydrogenation of easily reduced group-decorated alkynes and nitroarenes with high chemoselectivity is realized. (iv) For gas reactant participated reactions, by designing hydrophobic gas diffusion...

Carbon-doped In2S3 is a photocatalyst for converting CO2–H2O to C2H4 without any sacrificial agents. Carbon doping can enhance water adsorption/dissociation and CO2 activation and decrease energy barriers of forming CH* intermediates, resulting in high selectivity.

Electrocatalytic semihydrogenation of acetylene provides a clean pathway to produce ethylene (C 2 H 4 ), one of the most widely used petrochemical feedstocks, but its performance is still well below that of the thermocatalytic route, leaving its practical feasibility questionable. Here our techno-economic analysis shows that this process becomes pro table if the Faraday e ciency (FE) exceeds 85% at a current density of 0.2 A cm −2 . As a result, we design a Cu nanoparticle catalyst with coordinatively unsaturated sites to steer the reaction towards these targets. Remarkably, our electrocatalyst synthesized on gas diffusion layer-coated carbon paper enables a high C 2 H 4 yield rate of 70.15 mmol mg −1 h −1 and a FE of 97.7% at an industrially relevant current density of 0.5 A cm −2 . Combined characterizations and calculations reveal that such performance can be attributed to a favorable combination of a higher energy barrier for coupling of active hydrogen atoms (H*) and weak absorption of *C 2 H 4 . The former serves to suppress the competitive hydrogen evolution reaction, whereas the latter avoids overhydrogenation and C-C coupling. Further life cycle assessment evidences the economic feasibility and sustainability of the process. Our work suggests a way towards rational design and manipulation of nanocatalysts that could nd wider and greener catalytic applications.

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