Anodic oxygen evolution reaction (OER) is recognized as kinetic bottleneck in water electrolysis. Transition metal sites with high valence states can accelerate the reaction kinetics to offer highly intrinsic activity, but suffer from thermodynamic formation barrier. Here, we show subtle engineering of highly oxidized Ni 4+ species in surface reconstructed (oxy) hydroxides on multicomponent FeCoCrNi alloy film through interatomically electronic interplay. Our spectroscopic investigations with theoretical studies uncover that Fe component enables the formation of Ni 4+ species, which is energetically favored by the multistep evolution of Ni 2+ →Ni 3+ →Ni 4+. The dynamically constructed Ni 4+ species drives holes into oxygen ligands to facilitate intramolecular oxygen coupling, triggering lattice oxygen activation to form Fe-Ni dual-sites as ultimate catalytic center with highly intrinsic activity. As a result, the surface reconstructed FeCoCrNi OER catalyst delivers outstanding mass activity and turnover frequency of 3601 A g metal −1 and 0.483 s −1 at an overpotential of 300 mV in alkaline electrolyte, respectively.

Incorporating carbon into Bi3 O4 Cl enhances its internal electric field by 126 times, which induces a bulk charge separation efficiency (ηbulk ) of 80%. This ultrahigh ηbulk value presents a state-of-the-art result in tuning the bulk charge separation. The generated C-doped Bi3 O4 Cl has a noble-metal- and electron-scavenger-free water-oxidation ability under visible light, which is difficult to achieve with most existing photocatalysts.

Replacement of precious metals with earth‐abundant electrocatalysts for oxygen evolution reaction (OER) holds great promise for realizing practically viable water‐splitting systems. It still remains a great challenge to develop low‐cost, highly efficient, and durable OER catalysts. Here, the composition and morphology of Ni–Co bimetal phosphide nanocages are engineered for a highly efficient and durable OER electrocatalyst. The nanocage structure enlarges the effective specific area and facilitates the contact between catalyst and electrolyte. The as‐prepared Ni–Co bimetal phosphide nanocages show superior OER performance compared with Ni2P and CoP nanocages. By controlling the molar ratio of Ni/Co atoms in Ni–Co bimetal hydroxides, the Ni0.6Co1.4P nanocages derived from Ni0.6Co1.4(OH)2 nanocages exhibit remarkable OER catalytic activity (η = 300 mV at 10 mA cm−2) and long‐term stability (10 h for continuous test). The density‐functional‐theory calculations suggest that the appropriate Co doping concentration increases density of states at the Fermi level and makes the d‐states more close to Fermi level, giving rise to high charge carrier density and low intermedia adsorption energy than those of Ni2P and CoP. This work also provides a general approach to optimize the catalysis performance of bimetal compounds.

Electrocatalytic oxygen evolution reaction (OER) is a key process in electrochemical energy conversion and storage. Cobalt-containing spinel oxides are promising candidates for OER, but suffer from cation deficiency during OER, because of the high stability and reversibility of the spinel structure. Herein, we combine catalytically inactive CeO 2 and spinel structure Co 3 O 4 (CeO 2 /Co 3 O 4 ) by a built-in p−n heterojunction. The strongly coupled p−n heterojunction interface allows a rapid interfacial charge transfer from CeO 2 to Co 3 O 4 , which leads to a high concentration of oxygen vacancies and the generation of Co 2+ octahedral (Co 2+ (O h )) sites from the reduction of Co 3+ (O h ) at the CeO 2 /Co 3 O 4 interface. Consequently, the CeO 2 /Co 3 O 4 interface with the optimal ratio of Ce/Co exhibits high OER activity with an overpotential of only 265 mV at the current density of 10 mA cm −2 , a Tafel slope of 68.1 mV dec −1 , and long-term durability in an alkaline medium.

Enhancing catalytic activity by decorating noble metals in catalysts provides an opportunity for promoting the electrocatalytic hydrogen evolution reaction (HER) application. However, there are few systematic studies on regulating the structures of noble metals in catalytic materials and investigating their influence on HER. Herein, Pt catalysts with different structures including single atoms (SAs), clusters, and nanoparticles well-controllably anchored on VS2 nanosheets through a cost-effective optothermal method are reported, and their HER performance is studied. The most efficient Pt-decorated VS2 catalyst (with both Pt SAs and clusters) delivers an overpotential of 77 mV at 10 mA cm–2, close to that of Pt/C (48 mV). However, the optimal mass activity of Pt (normalizing to Pt content) is obtained from only SA Pt-decorated VS2 (i.e., 22.88 A mgPt –1 at 200 mV) and is 12 times greater than that of the Pt/C (1.87 A mgPt –1), attributed to the greatly enhanced Pt utilization. Additionally, the theoretical simulations reveal that Pt SA decoration makes the adsorption free energy of H* closer to the thermoneutral value and improves the charge-transfer kinetics, significantly enhancing HER activity. This work offers a pathway to prepare the desired catalyst based on synergy of Pt structures and VS2 and reveals the intrinsic mechanism for enhancing catalytic activity, which is important for HER applications.

Photocatalytic reduction of CO holds great promises for addressing both the environmental and energy issues that are facing the modern society. The major challenge of CO photoreduction into fuels such as methane or methanol is the low yield and poor selectivity. Here, we report an effective strategy to enhance the reduction potential of photoexcited electrons by fluorination of mesoporous single crystals of reduced TiO. Density functional theory calculations and photoelectricity tests indicate that the Ti impurity level is upswept by fluorination, owing to the built-in electric field constructed by the substitutional F that replaces surface oxygen vacancies, which leads to the enhanced reduction potential of photoexcited electrons. As a result, the fluorination of the reduced TiO dramatically increases the CH production yield by 13 times from 0.125 to 1.63 μmol/g·h under solar light illumination with the CH selectivity being improved from 25.7% to 85.8%. Our finding provides a metal-free strategy for the selective CH generation from CO photoreduction.

Semiconductor photocatalysts have been widely used for photochemical water splitting, purification of organic contaminants, and bacterial detoxification. However, most photocatalysts suffer greatly from photocorrosion under visible-light irradiation. Here we report a viable strategy to markedly improve photocorrosion resistance of photocatalysts by draping ultrathin yet highly impermeable graphene layers over a semiconductor CdS electrode. Remarkably, the average lifetime of three-layer-graphene-draped CdS photocatalyst is prolonged by 8 times compared to the as-prepared CdS counterpart without graphene draping. The introduction of graphene layers largely suppresses the charge carrier recombination of the CdS film and decreases the carrier transfer resistance at the graphene-draped CdS electrode/electrolyte interface, as revealed by the photoluminescence (PL) and electrochemical impedance spectroscopy studies, respectively, thereby leading to increased photocurrent and enhanced photocatalytic performance (i.e., a 2.5-fold increase in comparison to that in as-prepared CdS case). Our density functional theory calculations also show that electrons are readily transferred from CdS to graphene, correlating well with the PL measurement. The photocorrosion is mainly caused by oxidation reaction between CdS and O and HO assisted with photogenerated holes, evidenced by X-ray photoelectron spectroscopy characterization. The draped graphene effectively prevents the direct contact between the CdS film and O and HO, thus considerably retarding the photocorrosion of CdS upon visible-light exposure. This simple yet robust graphene-draping strategy for antiphotocorrosion of semiconductor photocatalysts is environmentally friendly as it prevents them from entering into the surrounding environment, thus eliminating the possible secondary pollution.

To alleviate photoinduced charge recombination in semiconducting nanomaterials represents an important endeavor toward high‐efficiency photocatalysis. Here a judicious integration of piezoelectric and photocatalytic properties of organolead halide perovskite CH3NH3PbI3 (MAPbI3) to enable a piezophotocatalytic activity under simultaneous ultrasonication and visible light illumination for markedly enhanced photocatalytic hydrogen generation of MAPbI3 is reported. The conduction band minimum of MAPbI3 is higher than hydrogen generation potential (0.046 V vs normal hydrogen electrode), thereby rendering efficient hydrogen evolution. In addition, the noncentrosymmetric crystal structure of MAPbI3 enables its piezoelectric properties. Thus, MAPbI3 readily responds to external mechanical force, creating a built‐in electric field for collective piezophotocatalysis as a result of effective separation of photogenerated charge carriers. The experimental results show that MAPbI3 powders exhibit superior piezophotocatalytic hydrogen generation rate (23.30 µmol h−1) in hydroiodic acid (HI) solution upon concurrent light and mechanical stimulations, much higher than that of piezocatalytic (i.e., 2.21 µmol h−1) and photocatalytic (i.e., 3.42 µmol h−1) hydrogen evolution rate as well as their sum (i.e., 5.63 µmol h−1). The piezophotocatalytic strategy provides a new way to control the recombination of photoinduced charge carriers by cooperatively capitalizing on piezocatalysis and photocatalysis of organolead halide perovskites to yield highly efficient piezophotocatalysis.